View source for Islamic calendar

{{Short description|Lunar calendar used by most Muslims}}
{{About|the Hijri calendar based on lunar observation|the solar calendar whose first year is fixed to the Hijra|Solar Hijri calendar|the rule-based Hijri calendar|Tabular Islamic calendar}}
{{redirect|Crescent moon of Islam| the symbol| Star and crescent}}
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[[File: King Khaled airport exit stamp.jpg|thumbnail|Islamic calendar stamp issued at [[King Khalid International Airport]] on 10 Rajab 1428 AH (24 July 2007 CE)]]
The '''Hijri calendar''' ({{langx|ar|ٱلتَّقْوِيم ٱلْهِجْرِيّ|translit=al-taqwīm al-hijrī}}), also known in English as the '''Islamic calendar''', is a [[lunar calendar]] consisting of 12 [[lunar month]]s in a year of 354 or 355 days. It is used to determine the proper days of [[Islamic holiday]]s and rituals, such as the [[Ramadan|annual fasting]] and the annual season for the [[Hajj|great pilgrimage]]. In almost all countries where the predominant religion is Islam, the [[civil calendar]] is the [[Gregorian calendar]], with [[Assyrian calendar|Syriac month-names]] used in the [[Arabic names of calendar months#Levant and Mesopotamia|Levant and Mesopotamia]] ([[Iraq]], [[Syria]], [[Jordan]], [[Lebanon]] and [[Palestine]]), but the religious calendar is the Hijri one.

This calendar enumerates the [[Hijri era]], whose [[Epoch (reference date)|epoch]] was established as the [[Islamic New Year]] in 622 [[Common Era|CE]].<ref>{{cite magazine |url=https://www.soundvision.com/article/the-beginning-of-hijri-calendar |title=The Beginning of Hijri calendar |author=Paul Lunde |magazine=[[Saudi Aramco World Magazine]] |issue=November/December 2005 |access-date=1 January 2019 |archive-date=1 January 2019 |archive-url=https://web.archive.org/web/20190101193832/https://www.soundvision.com/article/the-beginning-of-hijri-calendar |url-status=live }}</ref> During that year, [[Muhammad]] and his followers migrated from [[Mecca]] to [[Medina]] and established the first Muslim community (''[[ummah]]''), an event commemorated as the [[Hijrah]]. In the West, dates in this era are usually denoted '''AH''' ({{langx|la|Anno Hegirae|lit=In the year of the Hijrah}}).{{efn|This notation is similar to that of [[Anno Domini|AD]] for the [[Christian era]], [[Common Era|CE]] for the [[Common Era]] and [[Anno Mundi|AM]] for the [[Jewish era]].}} In Muslim countries, it is also sometimes denoted as '''H'''<ref name="WH">{{cite encyclopedia|author=Watt, W. Montgomery|editor1=P.J. Bearman|editor2=Th. Bianquis|editor3=[[Clifford Edmund Bosworth|C.E. Bosworth]]|editor4=E. van Donzel|editor5=W.P. Heinrichs|encyclopedia=[[Encyclopaedia of Islam]] Online|title=Hidjra|publisher=Brill Academic Publishers|issn=1573-3912}}</ref> from its Arabic form ({{lang|ar|سَنَة هِجْرِيَّة}}, abbreviated {{lang|ar|ھ}}). In English, years prior to the Hijra are denoted as '''BH''' ("Before the Hijra").<ref>{{cite web |url=http://www.sharjah.ae/registration-locations.aspx?Val=111 |title=Hijri Calendar |publisher=[[Government of Sharjah]] |access-date=21 January 2017 |archive-url=https://web.archive.org/web/20170202005514/http://www.sharjah.ae/registration-locations.aspx?Val=111 |archive-date=2 February 2017 |url-status=dead }}.</ref>

Since 26 June 2025 CE, {{Update after|2026|06|16||reason="current year" needs to be changed to 1448, the start and finish dates need to be revised and the citations need to be replaced [drop the old 2025 one, add a new one for 2026]. Finally this 'update after' needs itself to be reset for 2026 CE|text=the current Islamic year is 1447&nbsp;AH}}.  In the [[Gregorian calendar]] reckoning, 1447&nbsp;AH runs from 26&nbsp;June&nbsp;2025 to approximately 15&nbsp;June&nbsp;2026.<ref>{{cite web |title=Important dates in Islamic Calendar in the Year 2025 |url=https://www.al-habib.info/islamic-calendar/global/global-islamic-calendar-year-2025-ce.htm#hijrievents |website=Al-Habib.info |access-date=27 June 2025}}</ref><ref>{{cite web |title=Important dates in Islamic Calendar in the Year 2026 |url=https://www.al-habib.info/islamic-calendar/global/global-islamic-calendar-year-2026-ce.htm#hijrievents |website=Al-Habib.info |access-date=27 June 2025}}</ref>{{efn|exact dates depend on which variant of the Islamic calendar is followed.}}

==History==
{{For|a list of Islamic centuries and the corresponding Gregorian years|Timeline of Islamic history}}

===Pre-Islamic calendar===
{{Main|Pre-Islamic calendar}}
For central Arabia, especially [[Mecca]], there is a lack of epigraphical evidence but details are found in the writings of Muslim authors of the [[Abbasid]] era. Inscriptions of the ancient [[South Arabia]]n calendars reveal the use of a number of local calendars. At least some of these South Arabian calendars followed the [[lunisolar calendar|lunisolar system]]. Both [[al-Biruni]] and [[al-Mas'udi]] suggest that the ancient Arabs used the same month names as the Muslims, though they also record other month names used by the pre-Islamic Arabs.<ref name="EI2-Tarikh"/>{{which|date=March 2021}}

The Islamic tradition is unanimous in stating that Arabs of [[Tihamah]], [[Hejaz]], and [[Najd]] distinguished between two types of months, permitted (''ḥalāl'') and forbidden (''ḥarām'') months.<ref name="EI2-Tarikh"/> The forbidden months were four months during which fighting is forbidden, listed as Rajab and the three months around the [[hajj|pilgrimage]] season, Dhu al-Qa‘dah, Dhu al-Hijjah, and Muharram.<ref name="EI2-Tarikh"/> A similar if not identical concept to the forbidden months is also attested by [[Procopius]], where he describes an armistice that the Eastern Arabs of the Lakhmid al-Mundhir respected for two months in the [[summer solstice]] of 541 CE.<ref name="EI2-Tarikh"/> However, Muslim historians do not link these months to a particular season. The [[Qur'an]] links the four forbidden months with ''Nasī{{'}}'', a word that literally means "postponement".<ref name="EI2-Tarikh"/> According to Muslim tradition, the decision of postponement was administered by the tribe of [[Kinanah]],<ref name=Moberg2/> by a man known as the ''al-Qalammas'' of Kinanah and his descendants (pl. ''qalāmisa'').<ref name=Kitab/>

Different interpretations of the concept of ''Nasī{{'}}'' have been proposed.<ref>For an overview of the various theories and a discussion of the problem of "hindsight chronology" in early and pre-Islamic sources, see [http://etheses.dur.ac.uk/978/1/978.pdf?EThOS%20(BL) Maurice A. McPartlan, ''The Contribution of Qu'rān and Hadīt to Early Islamic Chronology'' (Durham, 1997)] {{Webarchive|url=https://web.archive.org/web/20131105220706/http://etheses.dur.ac.uk/978/1/978.pdf?EThOS%20(BL) |date=5 November 2013 }}.</ref> Some scholars, both Muslim<ref>Mahmud Effendi (1858), as discussed in Sherrard Beaumont Burnaby, ''[https://archive.org/details/elementsofjewish00burnuoft Elements of the Jewish and Muhammadan calendars]'' (London: 1901), pp. 460–470.</ref><ref>According to "Tradition", repeatedly cited by F.C. De Blois.</ref> and Western,<ref name="EI2-Tarikh">F.C. De Blois, "TA’RĪKH": I.1.iv.  "Pre-Islamic and agricultural calendars of the Arabian peninsula", ''The Encyclopaedia of Islam'', 2nd edition, '''X''':260.</ref><ref name=Moberg2>A. Moberg, "NASI'", ''The Encyclopaedia of Islam'', 2nd, VII: 977.</ref> maintain that the [[Pre-Islamic Arabia|pre-Islamic]] calendar used in central Arabia was a purely lunar calendar similar to the modern Islamic calendar. According to this view, ''Nasī{{'}}'' is related to the pre-Islamic practices of the Meccan Arabs, where they would alter the distribution of the forbidden months within a given year without implying a calendar manipulation. This interpretation is supported by Arab historians and lexicographers, like [[Ibn Hisham]], [[Ibn Manzur]], and the corpus of [[tafsir|Qur'anic exegesis]].<ref>{{Cite book|edition=4th|publisher=Al-maktaba al-tijāriyya|last=Muḥammad al-Khuḍarī Bayk|title=Muḥāḍarāt tārīkh al-Umam al-Islāmiyya|year=1935|pages=59–60|volume=2}}</ref>

This is corroborated by an early [[Sabaic]] inscription, where a religious ritual was "postponed" (''ns'w'') due to war. According to the context of this inscription, the verb ''ns'’'' has nothing to do with intercalation, but only with moving religious events within the calendar itself. The similarity between the religious concept of this ancient inscription and the Qur'an suggests that non-calendaring postponement is also the Qur'anic meaning of ''Nasī{{'}}''.<ref name="EI2-Tarikh"/> The ''[[Encyclopaedia of Islam]]'' concludes "The Arabic system of [Nasī'] can only have been intended to move the Hajj and the fairs associated with it in the vicinity of Mecca to a suitable season of the year. It was not intended to establish a fixed calendar to be generally observed."<ref>The Encyclopedia of Islam, 2nd edition, Index, p. 441.</ref> The term "fixed calendar" is generally understood to refer to the non-intercalated calendar.

Others concur that it was originally a lunar calendar, but suggest that about 200 years before the [[Hijra (Islam)|Hijra]] it was transformed into a [[lunisolar calendar]] containing an [[Intercalation (timekeeping)|intercalary month]] added from time to time to keep the pilgrimage within the season of the year when merchandise was most abundant. This interpretation was first proposed by the medieval Muslim astrologer and astronomer [[Abu Ma'shar al-Balkhi]], and later by [[al-Biruni]],<ref name=Kitab>[[Ja'far ibn Muhammad Abu Ma'shar al-Balkhi|Abu Ma'shar al-Balkhi]] (787–886), ''[http://gallica.bnf.fr/ark:/12148/bpt6k93171b.image.f166.langFR Kitab al-Uluf] {{Webarchive|url=https://web.archive.org/web/20110703090924/http://gallica.bnf.fr/ark:/12148/bpt6k93171b.image.f166.langFR |date=3 July 2011 }}'', ''Journal Asiatique'', series 5, '''xi''' (1858) 168+. {{in lang|fr|ar}}</ref><ref name="Nasi">{{cite book |url=https://archive.org/details/chronologyofanci00biru |last=al-Biruni |first=Abu Rayhan Muhammad ibn Ahmad |author-link= al-Biruni|translator-last= Sachau |translator-first=C. Edward |translator-link=Eduard Sachau|title="Intercalation of the Ancient Arabs", The Chronology of Ancient Nations |year=1879 |location=London |publisher=William H. Allen|pages=[https://archive.org/details/chronologyofanci00biru/page/13 13]–14, 73–74}}</ref> [[al-Mas'udi]], and some western scholars.<ref name=Moberg1>A. Moberg, "[https://books.google.com/books?id=9JQ3AAAAIAAJ NASI']", ''E.J. Brill's first encyclopaedia of Islam''.</ref> This interpretation considers ''Nasī{{'}}'' to be a synonym to the Arabic word for "intercalation" (''kabīsa''). The Arabs, according to one explanation mentioned by Abu Ma'shar, learned of this type of intercalation from the Jews.<ref name=Moberg2/><ref name=Kitab/><ref name="Nasi"/> The Jewish ''Nasi'' was the official who decided when to intercalate the Jewish calendar.<ref>Bab. Talmud, Sanhedrin, p. 11.</ref>{{Full citation needed|date=August 2022}} Some sources say that the Arabs followed the Jewish practice and intercalated seven months over nineteen years, or else that they intercalated nine months over 24 years; there is, however, no consensus among scholars on this issue.<ref>Bonner 2011, page 21.</ref>{{Full citation needed|date=August 2022}}

===Prohibiting Nasī' <span class="anchor" id="Prohibiting Nasi'"></span><span class="anchor" id="Prohibiting Nasi"></span>===
{{further|Nasi'}}
<!----Please see [[Talk:Muhammad/FAQ]] and discuss on the talk page before removing the following image:---->[[File:Maome.jpg|thumb|Illustration of Muhammad prohibiting Nasī'. Found in an illustrated copy of [[Abū Rayḥān al-Bīrūnī|Al-Biruni]]'s ''[[The Remaining Signs of Past Centuries]]'' (17th-century copy of an early 14th-century [[Ilkhanate|Ilkhanid]] manuscript).<ref>From an illustrated manuscript of Al-Biruni's 11th-century ''[[Vestiges of the Past]]'' (Bibliothèque Nationale, Paris, Arabe 1489 fol. 5v. (Bibliothèque Nationale on-line catalog). See also: Robert Hillenbrand, "Images of Muhammad in al-Bīrūnī's Chronology of Ancient Nations", in: R. Hillenbrand (ed.), ''Persian Painting from the Mongols to the Qajars: Studies in Honour of Basil W. Robinson'' (London/New York: I.B. Tauris Publishers, 2000), pp. 129–46.</ref>]]

[[Nasi']] is interpreted to signify either the postponement of the pre-Islamic month of Hajj, or the (also pre-Islamic) practice of [[intercalation (timekeeping)|intercalation]]{{snd}} periodic insertion of an additional month to reset the calendar into accordance with the seasons.

In the tenth year of the Hijra, as documented in the [[Qur'an]] ([[At-Tawba|Surah At-Tawbah (9)]]:36–37), Muslims believe [[God in Islam|God]] revealed the "prohibition of the Nasī{{'"}}.

{{Blockquote|Indeed, the number of months ordained by Allah is twelve—in Allah's Record since the day He created the heavens and the earth—of which four are sacred. That is the Right Way. So do not wrong one another during these months. And together fight the polytheists as they fight against you together. And know that Allah is with those mindful ˹of Him˺.<br>
Reallocating the sanctity of ˹these˺ months is an increase in disbelief, by which the disbelievers are led ˹far˺ astray. They adjust the sanctity one year and uphold it in another, only to maintain the number of months sanctified by Allah, violating the very months Allah has made sacred. Their evil deeds have been made appealing to them. And Allah does not guide the disbelieving people.|{{qref|9|36|c=y}}}}

The prohibition of Nasī' would presumably have been announced when the intercalated month had returned to its position just before the month of Nasi' began. If Nasī' meant intercalation, then the number and the position of the intercalary months between AH 1 and AH 10 are uncertain; western calendar dates commonly cited for key events in early Islam such as the [[Hegira|Hijra]], the [[Battle of Badr]], the [[Battle of Uhud]] and the [[Battle of the Trench]] should be viewed with caution as they might be in error by one, two, three or even four lunar months. This prohibition was mentioned by Muhammad during the [[The Farewell Sermon|farewell sermon]] which was delivered on 9 Dhu al-Hijjah AH 10 (Julian date Friday 6 March 632 CE) on [[Mount Arafat]] during the [[The Farewell Pilgrimage|farewell pilgrimage]] to Mecca.{{citation needed|date=October 2016}}

{{blockquote|Certainly the Nasi' is an impious addition, which has led the infidels into error. One year they authorise the Nasi', another year they forbid it. They observe the divine precept with respect to the number of the sacred months, but in fact they profane that which God has declared to be inviolable, and sanctify that which God has declared to be profane. Assuredly time, in its revolution, has returned to such as it was at the creation of the heavens and the earth. In the eyes of God the number of the months is twelve. Among these twelve months four are sacred, namely, Rajab, which stands alone, and three others which are consecutive.|Translated by Sherrard Beaumont Burnaby<ref>Sherrard Beaumont Burnaby, ''[https://archive.org/details/elementsofjewish00burnuoft Elements of the Jewish and Muhammadan calendars]'' (London: 1901) 370.</ref>}}

The three successive sacred (forbidden) months mentioned by Muhammad (months in which battles are forbidden) are [[Dhu al-Qadah|Dhu al-Qa'dah]], [[Dhu al-Hijjah]], and [[Muharram]], months 11, 12, and 1 respectively. The single forbidden month is [[Rajab]], month 7. These months were considered forbidden both within the new Islamic calendar and within the old pagan Meccan calendar.<ref>{{cite news |title=Islamic New Year: To celebrate, or not to celebrate? |url=https://nation.com.pk/05-Oct-2016/islamic-new-year-to-celebrate-or-not-to-celebrate |work=The Nation |date=5 October 2016 |language=en |access-date=20 August 2020 |archive-date=10 August 2021 |archive-url=https://web.archive.org/web/20210810091710/https://nation.com.pk/05-Oct-2016/islamic-new-year-to-celebrate-or-not-to-celebrate |url-status=live }}</ref><ref name="EI2-Tarikh"/><ref>{{cite news |title=The four sacred months |url=https://saudigazette.com.sa/article/152932 |work=Saudigazette |date=15 April 2016 |language=en |access-date=21 August 2020 |archive-date=10 August 2020 |archive-url=https://web.archive.org/web/20200810220521/https://saudigazette.com.sa/article/152932 |url-status=live }}</ref><ref>{{cite news |title=Muharram 2020: Al Hijri date, significance of the Islamic New Year |url=https://www.hindustantimes.com/more-lifestyle/muharram-2020-al-hijri-date-and-significance-of-the-islamic-new-year/story-XfqdLHudDcI20RVWKQtOzL.html |work=[[Hindustan Times]] |date=20 August 2020 |language=en |access-date=21 August 2020 |archive-date=21 August 2020 |archive-url=https://web.archive.org/web/20200821071634/https://www.hindustantimes.com/more-lifestyle/muharram-2020-al-hijri-date-and-significance-of-the-islamic-new-year/story-XfqdLHudDcI20RVWKQtOzL.html |url-status=live }}</ref><ref>{{cite web |title=The beginning of a new Islamic year |url=https://gulf-times.com/story/671105/The-beginning-of-a-new-Islamic-year |website=Gulf-Times |language=ar |date=20 August 2020 |access-date=21 August 2020 |archive-date=21 August 2020 |archive-url=https://web.archive.org/web/20200821072520/https://gulf-times.com/story/671105/The-beginning-of-a-new-Islamic-year |url-status=live }}</ref>

==Days of the week==
Traditionally, the Islamic day begins at sunset and ends at the next sunset. Each Islamic day thus begins at nightfall and ends at the end of daylight.

The days in the seven-day week are, with the exception of the last two days, named after their ordinal place in the week.

On the sixth day of the week, the "gathering day" ({{transliteration|ar|Yawm al-Jumʿah}}), Muslims assemble for the Friday-prayer at a local mosque at noon. The "gathering day" is often regarded as the weekly day off. This is frequently made official, with many Muslim countries adopting Friday and Saturday (e.g., Egypt, Saudi Arabia) or Thursday and Friday as official [[weekends]], during which offices are closed; other countries (e.g., Iran) choose to make Friday alone a day of rest. A few others (e.g., Turkey, Pakistan, Morocco, Nigeria, Malaysia) have adopted the Saturday-Sunday weekend while making Friday a working day with a long midday break to allow time off for worship.{{citation needed|date=October 2016}}

{{clear}}
{| class="wikitable" style="text-align: center"
! No. !! Name !! Arabic !! Meaning !! English equivalent
|-
| 1 || al-ʾAḥad || style="direction:rtl;" | {{script/Arabic|ٱلْأَحَد}} || the One || Saturday night and Sunday daytime
|-
| 2 || al-Ithnayn || style="direction:rtl;" | {{script/Arabic|الاِثْنَيْن}} || the Second || Sunday night and Monday daytime
|-
| 3 || ath-Thulāthāʾ || style="direction:rtl;" | {{script/Arabic|ٱلثُّلَاثَاء}} || the Third || Monday night and Tuesday daytime
|-
| 4 || al-ʾArbiʿāʾ || style="direction:rtl;" | {{script/Arabic|ٱلْأَرْبِعَاء}} || the Fourth || Tuesday night and Wednesday daytime
|-
| 5 || al-Khamīs || style="direction:rtl;" | {{script/Arabic|ٱلْخَمِيس}} || the Fifth || Wednesday night and Thursday daytime
|-
| 6 || al-Jumʿah || style="direction:rtl;" | {{script/Arabic|ٱلْجُمْعَة}} || the Gathering || Thursday night and Friday daytime
|-
| 7 || as-Sabt || style="direction:rtl;" | {{script/Arabic|ٱلسَّبْت}} || [[Sabbath#Islam|the Rest]] || Friday night and Saturday daytime
|}

==Months <span class="anchor" id="Length of months"></span><span class="anchor" id="Hilal"></span>==
Each month of the Islamic calendar commences on the birth of the new lunar cycle.<ref name="Navy Almanac" /> Traditionally, this is based on actual observation of the moon's crescent ([[wikt:hilal#Noun|{{transliteration|ar|hilal}}]]) marking the end of the previous lunar cycle and hence the previous month, thereby beginning the new month. Consequently, each month can have 29 or 30 days depending on the visibility of the Moon, astronomical positioning of the Earth and weather conditions.{{efn|Certain sects and groups, most notably Bohras Muslims namely [[Alavi Bohras|Alavis]], [[Dawoodi Bohra|Dawoodis]] and [[Sulaymani]]s and [[Shia]] [[Ismaili]] Muslims, use a [[tabular Islamic calendar]] in which odd-numbered months have thirty days (and also the twelfth month in a leap year) and even months have 29. However this article is about the calendar used by Sunni Islam, in which there are no explicit leap years.}}

Four of the twelve Hijri months are considered sacred: {{transliteration|ar|Rajab}} (7), and the three consecutive months of {{transliteration|ar|Dhū al-Qa'dah}} (11), {{transliteration|ar|Dhu al-Ḥijjah}} (12) and {{transliteration|ar|Muḥarram}} (1), in which battles are forbidden.<ref>{{cite web|url=http://www.usc.edu/org/cmje/religious-texts/hadith/bukhari/054-sbt.php#004.054.419|title=Center for Muslim-Jewish Engagement|publisher=usc.edu |url-status=dead |archive-url=https://web.archive.org/web/20140828004318/http://www.usc.edu/org/cmje/religious-texts/hadith/bukhari/054-sbt.php#004.054.419|archive-date=28 August 2014}}</ref>

{{clear}}
{| class="wikitable sortable plainrowheaders" style="text-align: center"
|+{{Legend|#D0F0C0|[[Sacred months]]|outline=grey|size=20px}}
! scope="col" width="20" | No.
! scope="col" width="130" | Name
! scope="col" width="80" | Arabic
! scope="col" width="140" | Meaning
! Note
|-

|style="background:#D0F0C0; text-align:center;" | 1 ||style="background:#D0F0C0; text-align:center;" |[[Muharram|{{transliteration|ar|al-Muḥarram}}]] ||style="background:#D0F0C0; text-align:center;" | {{lang|ar|ٱلْمُحَرَّم}} ||style="background:#D0F0C0; text-align:center;" | forbidden ||style="background:#D0F0C0; text-align:center;" | A sacred month, so called because battle and all kinds of fighting are forbidden ({{transliteration|ar|ḥarām}}) during this month. Muharram includes [[Ashura]], the tenth day.
|-
| 2 || [[Safar|{{transliteration|ar|Ṣafar}}]] || {{lang|ar|صَفَر}} || void || Supposedly named this because pre-Islamic Arab houses were empty this time of year while their occupants gathered food.
|-
| 3 || [[Rabi' al-Awwal|{{transliteration|ar|Rabīʿ al-ʾAwwal}}]] || {{lang|ar|رَبِيع ٱلْأَوَّل}} || the first spring || Also means to graze, because cattle were grazed during this month. Also a very holy month of celebration for many Muslims, as it was the month Muhammad was born.<ref>{{cite web|url=http://www.minhaj.org/english/tid/9813/The-significance-of-the-12th-of-Rabi-al-Awwal.html|last=Hanif|first=Muhammad|title=The significance of the 12th of Rabi al – Awwal|date=18 February 2010|website=Minhaj – ul – Quran|access-date=14 June 2016|archive-date=15 January 2021|archive-url=https://web.archive.org/web/20210115023729/https://www.minhaj.org/english/tid/9813/The-significance-of-the-12th-of-Rabi-al-Awwal.html|url-status=live}}</ref>
|-
| 4 || [[Rabi' al-Thani|{{transliteration|ar|Rabīʿ ath-Thānī}}]]<br/>or<br/>{{transliteration|ar|Rabīʿ al-ʾĀkhir}} || {{lang|ar|رَبِيع ٱلثَّانِي}}<br/>or<br/>{{lang|ar|رَبِيع ٱلْآخِر}} || the second spring, the last spring ||
|-
| 5 || [[Jumada al-awwal|{{transliteration|ar|Jumādā al-ʾŪlā}}]] || {{lang|ar|جُمَادَىٰ ٱلْأُولَىٰ}} || the first of parched land || Often considered the pre-Islamic summer. {{transliteration|ar|Jumādā}} may also be related to a verb meaning "to freeze" and another account relates that water would freeze during this time of year.
|-
| 6 || [[Jumada al-Thani|{{transliteration|ar|Jumādā ath-Thāniyah}}]]<br/>or<br/>{{transliteration|ar|Jumādā al-ʾĀkhirah}} || {{lang|ar|جُمَادَىٰ ٱلثَّانِيَة}}<br/>or<br/>{{lang|ar|جُمَادَىٰ ٱلْآخِرَة}} || the second of parched land, the last of parched land ||
|-
|style="background:#D0F0C0; text-align:center;" | 7 ||style="background:#D0F0C0; text-align:center;" | {{transliteration|ar|[[Rajab]]}} ||style="background:#D0F0C0; text-align:center;" | {{lang|ar|رَجَب}} ||style="background:#D0F0C0; text-align:center;" | respect, honour ||style="background:#D0F0C0; text-align:center;" | This is the second sacred month in which fighting is forbidden. {{transliteration|ar|Rajab}} may also be related to a verb meaning "to remove", so called because pre-Islamic Arabs would remove the heads of their spears and refrain from fighting.
|-
| 8 || [[Sha'ban|{{transliteration|ar|Shaʿbān}}]] || {{lang|ar|شَعْبَان}}  || scattered || Marked the time of year when Arab tribes dispersed to find water. {{transliteration|ar|Sha‘bān}} may also be related to a verb meaning "to be in between two things". Another account relates that it was called thus because the month lies between Rajab and Ramadan.
|-
| 9 || [[Ramadan (calendar month)|{{transliteration|ar|Ramaḍān}}]] || {{lang|ar|رَمَضَان}} || burning heat || Burning is related to fasting as with an empty stomach one's worldly desire will burn.{{Citation needed|date=April 2023}} Supposedly so called because of high temperatures caused by the excessive heat of the sun.{{Citation needed|date=April 2023}} {{transliteration|ar|Ramaḍān}} is the most venerated month of the Hijri calendar. During this time, Muslims must [[fasting|fast]] and not do anything sinful from pre-dawn until sunset and should [[Zakat al-Fitr|give charity to the poor and needy]].
|-
| 10 || [[Shawwal|{{transliteration|ar|Shawwāl}}]] || {{lang|ar|شَوَّال}} || raised || Female [[camel]]s would normally be in calf at this time of year and raise their tails. At the first day of this month, the [[Eid al-Fitr]], "Festival of Breaking the Fast" begins, marking the end of [[fasting]] and the end of Ramadan.
|-
|style="background:#D0F0C0; text-align:center;" | 11 ||style="background:#D0F0C0; text-align:center;" | [[Dhu al-Qadah|{{transliteration|ar|Ḏū al-Qaʿdah}}]] ||style="background:#D0F0C0; text-align:center;" | {{lang|ar|ذُو ٱلْقَعْدَة}} ||style="background:#D0F0C0; text-align:center;" | the one of truce/sitting ||style="background:#D0F0C0; text-align:center;" | This is a holy month during which war is banned. People are allowed to defend themselves if attacked.
|-
|style="background:#D0F0C0; text-align:center;" | 12 ||style="background:#D0F0C0; text-align:center;" | [[Dhu al-Hijjah|{{transliteration|ar|Ḏū al-Ḥijjah}}]] ||style="background:#D0F0C0; text-align:center;" | {{lang|ar|ذُو ٱلْحِجَّة}} ||style="background:#D0F0C0; text-align:center;" | the one of pilgrimage ||style="background:#D0F0C0; text-align:center;" |During this month Muslim pilgrims from all around the world congregate at [[Mecca]] to visit the [[Kaaba]]. The Hajj is performed on the eighth, ninth and the tenth of this month. [[Day of Arafah]] takes place on the ninth of the month. [[Eid al-Adha]], the "Festival of the Sacrifice", begins on the tenth day and ends on the thirteenth, and this is a fourth holy month during which war is banned.
|}

=== Alternative names ===

==== Afghan lunar calendar ====
The "Afghan lunar calendar" refers to two distinct naming systems for the months of the Hijri calendar, one of which was used by the [[Pashtuns]] and the other by the [[Hazaras]]. They were in use until the time of [[Amanullah Khan]]'s reign, when the usage of the [[Solar Hijri Calendar]] was formalized across Afghanistan.<ref>{{Cite journal |last=Klaus |first=Ferdinand |date=1959 |title=Preliminary notes on Hazāra culture: The Danish Scientific Mission to Afghanistan 1953–55 |url=https://www.royalacademy.dk/Publications/Low/632_Ferdinand,%20Klaus.pdf |journal={{Interlanguage link|Historisk-filosofiske Meddelelser|qid=Q100906806}} |publisher=[[Royal Danish Academy of Sciences and Letters]] |publication-place=Copenhagen |volume=37 |issue=5 |pages=44–46 |quote=Until the time of Amānullāh, the Hazāras used the following terms to indicate the Mohammedan lunar months: ''Ashur'', (...) ''Safar'', ''Algho-i-awwal'', ''Algho-i-doyum'', ''Algho-i-seyum'', ''Algho-i-chārum'', ''Rejāb'', ''Shabo'', ''Ramazo'', ''Id mah'', ''Khāli'', ''Qurbo''.}}</ref><ref>{{Encyclopædia Iranica Online|year=1990|url=https://iranicaonline.org/articles/calendars#prettyPhoto[content]/20/|access-date=7 April 2024|first=Daniel|last=Balland|title=The Afghan lunar calendar}} "Pashto: Ḥasan-o-Ḥosayn, Ṣafara, Lumṛəy ḵо̄r, Dwayəma ḵо̄r, Drēyəma ḵо̄r, Calarəma ḵо̄r, Ḵodāytaʻālā myāšt, Barāt, Rо̄ža, Waṛakay aḵtar, Mīānī, Lо̄y aḵtar. Hazāragī: ʻĀšūr, Ṣafar, Alḡо̄-ye awwal, Alḡо̄-ye dovvom, Alḡо̄-ye sevvom, Alḡо̄-ye čahārom, Rajab, Ša'bо̄, Ramażо̄, ʻĪd, Ḵālī, Qorbо̄."</ref>

With effect from March 2022, the [[Government of Afghanistan]] has formally ceased use Solar Hijri calendar in favour of the Lunar Hijri calendar.<ref>{{Cite news |date=26 March 2022 |title=Taliban Changes Solar Year to Hijri Lunar Calendar |url=https://8am.af/eng/taliban-changes-solar-year-to-hijri-lunar-calendar/ |access-date=4 September 2022 |work=Hasht-e Subh Daily |url-status=dead |archive-url=https://web.archive.org/web/20220904224713/https://8am.af/eng/taliban-changes-solar-year-to-hijri-lunar-calendar/ |archive-date=4 September 2022}}</ref>{{disputed inline|talk=Talk:Solar Hijri calendar#Use in Afghanistan|date=August 2025}}

==== Turki lunar calendar ====
In [[Xinjiang]], the [[Uyghurs|Uyghur]] Muslims traditionally had different names for the months of the Hijri calendar, which were in use until the adoption of the Gregorian calendar in the 20th century.<ref>{{Cite book |last=Raquette |first=Gösta |author-link=Gösta Raquette |title=Mitteilungen des Seminars für Orientalische Sprachen an der Friedrich-Wilhelms-Universität zu Berlin |date=1912 |publisher={{ill|Georg Reimer publishing house|de|Verlag Georg Reimer}} |editor-last=Sachau |editor-first=Eduard |editor-link=Eduard Sachau |series=Part 2: Westasiatische Studien [West Asian Studies] |volume=15 |location=Berlin |pages=179–183 |trans-title=Notices from the Seminar for Oriental Languages at the Friedrich Wilhelm University in Berlin |chapter=Eastern Turki Grammar |quote=The Mohammedans only employ the Chinese system in documents to be presented before the Chinese authorities, otherwise they keep to their own. They have a Lunar year[.] (...) It has 12 months with 29 or 30 days. Their names, corresponding to the Arabic ones, (...) are as follows: {{lang|chg-Arab|عشور آی}} ''ʾä̬šu̬r ay'', {{lang|chg-Arab|صفر آی}} ''säpär ay'', {{lang|chg-Arab|صفر قوشنەسی}} ''säpär qošnä̬sı̬̊'', {{lang|chg-Arab|جمادی‌الاول}} ''ǰämadi ulä̬vä̬l'', {{lang|chg-Arab|جمادی‌الآخر}} ''ǰämadi ulaχir'', {{lang|chg-Arab|تلاش آی}} ''talaš ay'', {{lang|chg-Arab|دعا آی}} ''dʾu̥ā ay'', {{lang|chg-Arab|براعت آی}} ''baraʾt ay'', {{lang|chg-Arab|روزە آی}} ''roze ay'', {{lang|chg-Arab|عید آی}} ''ʾä̬yd ay'', {{lang|chg-Arab|آرا آی}} ''ārḁ ay'', {{lang|chg-Arab|عید قربان آی}} ''ʾä̬ydqurban ay''.}}</ref><ref>{{Cite book |last=Forsyth |first=Thomas Douglas |author-link=Thomas Douglas Forsyth |url=https://books.google.com/books?id=IpDxEAAAQBAJ&pg=PA512 |title=Report of a Mission to Yarkund in 1873, Under Command of Sir T. D. Forsyth: With Historical and Geographical Information Regarding the Possessions of the Ameer of Yarkund |date=1875 |publisher={{ill|Books on Demand (publisher)|fr|Books on Demand|lt=Books on Demand}} |isbn=978-3-385-25329-2 |page=512 |language=en |quote=The [c]alendar (...) is the same as the Muhammadan Almanac, the months and year being lunar[.] (...) The names of the lunar months and their corresponding Arabic ones are these: 'Ashúr Ay =  Muharram. Safar Ay = Safar. Safar Coshini Ay = Rabí'ulawwal. Jamádí-ul-awwal = Rabí-'uth-thání. Jamádí-ul-ákhir = Jamádí-ul-awwal. Talásh Ay = Jamádí-uth-thání. Duá Ay = Rajab. Barát Ay = Sha'bán. Roza Ay = Ramazán. Hít (Íd) Ay = Shawál. Ará Ay = Zi Ca'da. Hít Cúrbán Ay = Zi Híjja. |access-date=3 April 2024 |via=[[Google Books]]}}</ref><ref>{{Cite web |date=26 July 2014 |title=ھىجرىيە يىلنامىسى ھەققىدە قىسقىچە چۈشەنچە |trans-title=A brief description of the Hijri calendar |url=http://uyghur.chinaislam.net.cn/zongjiaoyuwenhua/yisilanzhishizhuji/201407/26-6524.html |access-date=2024-04-03 |website=[[Islamic Association of China]] |language=ug}}</ref> These names were collectively referred to as the "Turki lunar year" or "Turki lunar calendar".<ref>{{Cite book |last=Schwarz |first=Henry G. |url=https://cedar.wwu.edu/easpress/30/ |title=An Uyghur-English Dictionary |date=1992 |publisher=East Asian Studies Press |location=Bellingham, Washington |pages=1073–1074 |chapter=Calendars |volume=East Asian Research Aids & Translations, 3 |doi=10.25710/c1bm-2e85 |oclc=26635636 |quote=Turki Lunar Year: aşur ay, säpär ay, säpär qoşnisi, jamadi ulaval, jamadi ulaxir, talaş ay, du'a ay, barat ay, roza ay, heyt ay, ara ay, aydi qurban ay. |chapter-url=https://cedar.wwu.edu/cgi/viewcontent.cgi?filename=4&article=1029&context=easpress&type=additional |chapter-format=PDF}}</ref><ref>{{Cite book |last=Schluessel |first=Eric |url=http://niko.qalaymiqan.com/eastern_turki_glossary/ |title=Digital Glossary of Eastern Turki |date=2015 |chapter=Turki lunar year |access-date=3 April 2024}}</ref>
{| class="wikitable sortable plainrowheaders" style="text-align: center"
! rowspan="2" |No.
! rowspan="2" |Arabic name
! colspan="2" |Uyghur name
! rowspan="2" |Pashto name
! rowspan="2" |Hazaragi name
|-
![[Chagatai language|Chagatay]]
!Modern Uyghur
|-
|1
|{{langx|ar|المحرم|italic=no|translit=al-muḥarram|label=none}}
|{{langx|chg-Arab|عشور ای|translit=äşûr ay|label=none}}
|{{langx|ug-Arab|ئەشۇر ئاي|translit=eshur ay|label=none}}
|{{Langx|ps|حسن او حسین|translit=hasan aw husayn|label=none|italic=no}}
|{{Langx|fa|عاشور|label=none|translit=āšūr}}
|-
|2
|{{langx|ar|صفر|italic=no|translit=ṣafar|label=none}}
|{{langx|chg-Arab|صفر ای|translit=säfär ay|label=none}}
|{{langx|ug-Arab|سەپەر ئاي|translit=seper ay|label=none}}
|{{Langx|ps|صفره|translit=safara|label=none|italic=no}}
|{{Langx|fa|صفر|label=none|translit=safar}}
|-
|3
|{{langx|ar|ربيع الأول|italic=no|translit=rabīʿa l-ʾawwal|label=none}}
or

{{langx|ar|ربيع الأولى|italic=no|translit=rabīʿa l-ʾūlā|label=none}}
|{{langx|chg-Arab|صفر قوشنیسی|translit=säfär qoşnısı|label=none}}
|{{langx|ug-Arab|سەپەر قوشنىسى|translit=seper qoshnisi|label=none}}
|{{Langx|ps|لومړۍ خور|translit=lūmṛəy xor|label=none|italic=no}}
|{{Langx|fa|الغوی اول|label=none|translit=alğō-yi awwal}}
|-
|4
|{{langx|ar|ربيع الثاني|italic=no|translit=rabīʿa th-thānī|label=none}}
or

{{langx|ar|ربيع الآخر|italic=no|translit=rabīʿa l-ʾākhir|label=none}}
|{{langx|chg-Arab|جمادی‌الاول|translit=cämâdiyyul-ävväl|label=none}}
|{{langx|ug-Arab|جەمادىئۇل-ئەۋۋەل|translit=jemadiul-ewwel|label=none}}
|{{Langx|ps|دويمه خور|translit=dwayəma xor|label=none|italic=no}}
|{{Langx|fa|الغوی دویم|label=none|translit=alğō-yi duyum}}
|-
|5
|{{langx|ar|جمادى الأول|italic=no|translit=jumādā l-ʾawwal|label=none}}
or

{{langx|ar|جمادى الأولى|italic=no|translit=jumādā l-ʾūlā|label=none}}
|{{langx|chg-Arab|جمادی‌الآخر|translit=cämâdiyyul-âxir|label=none}}
|{{langx|ug-Arab|جەمادىئۇل-ئاخىر|translit=jemadiul-axir|label=none}}
|{{Langx|ps|درېيمه خور|translit=dreyəma xor|label=none|italic=no}}
|{{Langx|fa|الغوی سیم|label=none|translit=alğō-yi seyum}}
|-
|6
|{{langx|ar|جمادى الثانية|italic=no|translit=jumādā th-thāniyah|label=none}}
or

{{langx|ar|جمادى الآخرة|italic=no|translit=jumādā l-ʾākhirah|label=none}}
|{{langx|chg-Arab|تلاش ای|translit=talaş ay|label=none}}
|{{langx|ug-Arab|تالاش ئاي|translit=talash ay|label=none}}
|{{Langx|ps|څلرمه خور|translit=tsalarəma xor|label=none|italic=no}}
|{{Langx|fa|الغوی چارم|label=none|translit=alğō-yi čārum}}
|-
|7
|{{langx|ar|رجب|italic=no|translit=rajab|label=none}}
|{{langx|chg-Arab|دعا ای|translit=duâ ay|label=none}}
|{{langx|ug-Arab|دۇئا ئاي|translit=dua ay|label=none}}
|{{Langx|ps|خدای تعالی مياشت|translit=xudāy taālā myāšt|label=none|italic=no}}
|{{Langx|fa|رجب|label=none|translit=rajab}}
|-
|8
|{{langx|ar|شعبان|italic=no|translit=shaʿbān|label=none}}
|{{langx|chg-Arab|برائت ای|translit=bärâät ay|label=none}}
or

{{langx|chg-Arab|برات ای|translit=bärât ay|label=none}}
|{{langx|ug-Arab|بارات ئاي|translit=barat ay|label=none}}
|{{Langx|ps|برات|translit=barāt|label=none|italic=no}}
|{{Langx|fa|شعبو|label=none|translit=ša'bō}}
|-
|9
|{{langx|ar|رمضان|italic=no|translit=ramaḍān|label=none}}
|{{langx|chg-Arab|روزە ای|translit=rôzä ay|label=none}}
|{{langx|ug-Arab|روزا ئاي|translit=roza ay|label=none}}
|{{Langx|ps|روژه|translit=roža|label=none|italic=no}}
|{{Langx|fa|رمضو|label=none|translit=ramazō}}
|-
|10
|{{langx|ar|شوال|italic=no|translit=shawwāl|label=none}}
|{{langx|chg-Arab|عید ای|translit=ayd ay|label=none}}
|{{langx|ug-Arab|ھېيت ئاي|translit=hëyt ay|label=none}}
|{{Langx|ps|وړکی اختر|translit=waṛakay axtar|label=none|italic=no}}
|{{Langx|fa|عید|label=none|translit=īd}}
|-
|11
|{{langx|ar|ذو القعدة|italic=no|translit=ḏū l-qaʿdah|label=none}}
|{{langx|chg-Arab|آرا ای|translit=ara ay|label=none}}
|{{langx|ug-Arab|ئارا ئاي|translit=ara ay|label=none}}
|{{Langx|ps|مياني|translit=miyānī|label=none|italic=no}}
|{{Langx|fa|خالی|label=none|translit=xālī}}
|-
|12
|{{langx|ar|ذو الحجة|italic=no|translit=ḏū l-ḥijjah|label=none}}
|{{langx|chg-Arab|عید قربان ای|translit=aydi-qurbân ay|label=none}}
|{{langx|ug-Arab|ھېيتى-قۇربان ئاي|translit=hëyti-qurban ay|label=none}}
|{{Langx|ps|لوی اختر|translit=loy axtar|label=none|italic=no}}
|{{Langx|fa|قربو|label=none|translit=qurbō}}
|}

=== Alternative order ===
[[Twelver Shi'ism|Twelver Shia]] Muslims believe the [[Islamic New Year|Islamic new year]] and first month of the Hijri calendar is Rabi' al-Awwal rather than Muharram, due to it being the month in which the [[Hijrah]] took place.<ref>{{Cite web |last=Al-Hilli |first=Mohammed |date=22 September 2021 |title=Muharram May Not Be The Start Of The Islamic Hijri New Year |url=https://www.al-islam.org/media/muharram-may-not-be-start-islamic-hijri-new-year |access-date=13 April 2024 |website=[[Ahlul Bayt Digital Islamic Library Project]]}}</ref> This has led to difference regarding description of the years in which some events took place, such as the Muharram-occurring [[battle of Karbala]], which Shias say took place in 60 AH, while [[Sunni Islam|Sunnis]] say it took place in 61 AH.<ref>{{Cite journal |last=Rizvi |first=Sa'eed Akhtar |author-link=Sa'id Akhtar Rizvi |date=1401 |title=Martyrdom of Imam Husayn and the Muslim and Jewish Calendars |url=https://www.al-islam.org/al-serat/vol-6-no-3-4-1401ah/martyrdom-imam-husayn-and-muslim-and-jewish-calendars-sayyid-saeed-0 |journal=Al-Serat (A Journal of Islamic Studies) |volume=6 |issue=3–4 |access-date=13 April 2024 |via=[[Ahlul Bayt Digital Islamic Library Project]]}}</ref>

==Length of year==
The mean duration of a [[tropical year]] is 365.24219 days, while the long-term average duration of a [[lunar month#Synodic month|synodic month]] is 29.530587981 days. Thus the average lunar year (twelve new moons) is 10.87513 days shorter than the average solar year (365.24219 &minus; (12 × 29.530587981)), causing months of the Hijri calendar to advance about eleven days earlier each year, relative to the equinoxes.{{efn|The precise number varies, depending on the length of the [[synodic month]] (the time it takes the Moon to reach the same visual [[lunar phase|phase]]. This varies notably throughout the year.<ref name="AA">Jean Meeus, ''Astronomical Algorithms'' (Richmond, VA: Willmann-Bell, 1998) p 354. From 1900–2100, the shortest time from one new moon to the next is 29&nbsp;days, 6&nbsp;hours, and 35&nbsp;min, and the longest 29&nbsp;days, 19&nbsp;hours, and 55&nbsp;min.</ref>)}}  "As a result," says the ''[[Astronomical Almanac]]'', "the cycle of twelve lunar months regresses through the seasons over a period of about 33 &#91;[[tropical year|solar]]&#93; years".<ref name="Navy Almanac">{{Cite book|title=Explanatory Supplement to the Astronomical Almanac |last=Richards |first=E. G. |publisher=University Science Books |year=2012 |isbn=978-1-891389-85-6 |editor-last=Urban |editor-first=Sean E. |location=Mill Valley, CA |pages=606 |chapter=Calendars |editor-last2=Seidelmann |editor-first2=P. Kenneth |chapter-url=http://aa.usno.navy.mil/publications/docs/c15_usb_online.pdf |url-status=dead |archive-url=https://web.archive.org/web/20190430134555/http://aa.usno.navy.mil/publications/docs/c15_usb_online.pdf |archive-date=30 April 2019}}</ref>{{efn|This means that there are 34 Hijri years to 33 Gregorian years.}}

== Year numbering ==
{{Main|Hijri era}}
In pre-Islamic Arabia, it was customary to identify a year after a major event which took place in it. Thus, according to Islamic tradition, [[Abraha]], governor of Yemen, then a province of the Christian [[Kingdom of Aksum]] of [[Northeast Africa]] and [[South Arabia]], attempted to destroy the [[Kaaba]] with an army which included several elephants. The raid was unsuccessful, but that year became known as the ''[[Year of the Elephant]]'', during which Muhammad was born (surah [[al-Fil]]). Most equate this to the year 570 CE, but a minority use 571 CE.

The first ten years of the Hijra were not numbered, but were named after events in the life of Muhammad according to [[al-Biruni]]:<ref>Sherrard Beaumont Burnaby, [https://archive.org/details/elementsofjewish00burnuoft ''Elements of the Jewish and Muhammadan calendars''] (1901) 376.</ref>
# The year of permission.
# The year of the order of fighting.
# The year of the trial.
# The year of congratulation on marriage.
# The year of the earthquake.
# The year of enquiring.
# The year of gaining victory.
# The year of equality.
# The year of exemption.
# The year of farewell.

In {{Circa|638}} (17 AH), [[Abu Musa al-Ash'ari]], one of the officials of the [[Rashidun Caliphate|Rashid Caliph]] [[Umar]] ({{Reign|634|644}}) in [[Basra]], complained about the absence of any years on the correspondence he received from Umar, making it difficult for him to determine which instructions were most recent. This report convinced Umar of the need to introduce an era for Muslims. After debating the issue with his counsellors, he decided that the first year should be the year of Muhammad's arrival at Medina (known as Yathrib, before Muhammad's arrival).<ref>{{cite book | last1=Tillier | first1=Mathieu | chapter=Recording debts in Sufyānid Fusṭāṭ: a reexamination of the procedures and calendar in use in the first/seventh century | date=2019-04-11 | editor-last=Tolan | editor-first=John | title=Geneses: A comparative study of the historiographies of the rise of Christianity, Rabbinic Judaism, and Islam | pages=148–188 | location=New York | publisher=Routledge | isbn=978-1-351-11331-1 | last2=Vanthieghem | first2=Naïm | doi=10.4324/9781351113311-8 | url=https://halshs.archives-ouvertes.fr/halshs-02308264/file/Tillier-Vanthieghem-Recording%20debts-DEF.pdf | id={{HAL archive link|halshs-02308264v1}} | chapter-url=https://shs.hal.science/halshs-02308264/file/Tillier-Vanthieghem-Recording%20debts-DEF.pdf}}</ref> [[Uthman]] then suggested that the months begin with Muharram, in line with the established custom of the Arabs at that time. The years of the Islamic calendar thus began with the month of Muharram in the year of Muhammad's arrival at the city of Medina, even though the actual emigration took place in Safar and Rabi' I of the intercalated calendar, two months before the commencement of Muharram in the new fixed calendar.<ref name="WH"/> Because of the Hijra, the calendar was named the Hijri calendar.

F A Shamsi (1984) postulated that the Arabic calendar was never intercalated. According to him, the first day of the first month of the new fixed Islamic calendar (1 Muharram AH 1) was no different from what was observed at the time. The day the Prophet moved from Quba' to Medina was originally 26 Rabi' I on the pre-Islamic calendar.<ref>''Chronology of Prophetic Events'', Fazlur Rehman Shaikh (2001) p.52 Ta-Ha Publishers Ltd.</ref> 1 Muharram of the new fixed calendar corresponded to Friday, 16 July 622 CE, the equivalent civil tabular date (same daylight period) in the [[Julian calendar]].<ref>Sherrard Beaumont Burnaby, [https://archive.org/details/elementsofjewish00burnuoft ''Elements of the Jewish and Muhammadan calendars''] (1901) pp. 373–5, 382–4.</ref><ref>{{cite book | chapter=Table 1.2 Epochs for various calendars | chapter-url=https://books.google.com/books?id=cK1XDwAAQBAJ&pg=PA17 | page=17 | title=Calendrical Calculations | edition=Third | oclc=1137352777 | publisher=O'Reilly | first1=Nachum | last1=Dershowitz | first2=Edward | last2=Reingold | date=2018 | isbn=9781108546935 | access-date=21 March 2023 | archive-date=24 April 2023 | archive-url=https://web.archive.org/web/20230424000945/https://books.google.com/books?id=cK1XDwAAQBAJ&pg=PA17 | url-status=live}}</ref> The Islamic day began at the preceding sunset on the evening of 15 July. This Julian date (16 July) was determined by [[Astronomy in medieval Islam|medieval Muslim astronomers]] by projecting back in time their own [[tabular Islamic calendar]], which had alternating 30- and 29-day months in each lunar year plus eleven leap days every 30 years. For example, al-Biruni mentioned this Julian date in the year 1000 CE.<ref>al-Biruni, ''The chronology of ancient nations'', tr. [[C. Edward Sachau]] (1000/1879) 327.</ref> Although not used by either medieval Muslim astronomers or modern scholars to determine the Islamic epoch, the thin [[Lunar phase|crescent moon]] would have also first become visible (assuming clouds did not obscure it) shortly after the preceding sunset on the evening of 15 July, 1.5 days after the associated [[dark moon]] (astronomical [[new moon]]) on the morning of 14 July.<ref>{{cite web | url=http://eclipse.gsfc.nasa.gov/phase/phases0601.html | title=NASA phases of the moon 601–700 | url-status=dead | archive-url=https://web.archive.org/web/20101008214455/http://eclipse.gsfc.nasa.gov/phase/phases0601.html | archive-date=8 October 2010}}</ref>

Though [[Michael Cook (historian)|Michael Cook]] and [[Patricia Crone]] in their book ''[[Hagarism]]'' cite a coin from AH 17, the first surviving attested use of a Hijri calendar date alongside a date in another calendar ([[Coptic calendar|Coptic]]) is on a [[papyrus]] from [[Egypt]] in AH 22, [[PERF 558]].

==Astronomical considerations==
{{more citations needed section|date=October 2016}}
Due to the Islamic calendar's reliance on certain variable methods of observation to determine its month-start-dates, these dates sometimes vary slightly from the month-start-dates of the astronomical lunar calendar,{{Which|date=September 2022}} which are based directly on astronomical calculations. Still, the Islamic calendar roughly approximates the astronomical-lunar-calendar system, seldom varying by more than three days from it. Both the Islamic calendar and the astronomical-lunar-calendar take no account of the [[solar year]] in their calculations, and thus both of these strictly lunar based calendar systems have no ability to reckon the timing of the four seasons of the year.

In the astronomical-lunar-calendar system, a year of 12 lunar months is 354.37 days long. In this calendar system, lunar months begin precisely at the time of the monthly "conjunction", when the Moon is located most directly between the Earth and the Sun. The month is defined as the average duration of a revolution of the Moon around the Earth (29.53 days). By convention, months of 30 days and 29 days succeed each other, adding up over two successive months to 59 full days. This leaves only a small monthly variation of 44 minutes to account for, which adds up to a total of 24 hours (i.e., the equivalent of one full day) in 2.73 years. To settle accounts, it is sufficient to add one day every three years to the lunar calendar, in the same way that one adds one day to the Gregorian calendar every four years.<ref>Emile Biémont, Rythmes du temps, Astronomie et calendriers, De Borck, 2000, 393p.</ref> The technical details of the adjustment are described in [[Tabular Islamic calendar]].

The Islamic calendar, however, is based on a different set of conventions being used for the determination of the month-start-dates.<ref>{{cite web |url=http://tabsir.net/?p=633#more-633 |website=tabsir.net |title=Issues in the Islamic Calendar |first=Khalid |last=Chraibi |date=16 August 2008 |access-date=18 August 2008 |archive-date=6 October 2008 |archive-url=https://web.archive.org/web/20081006083025/http://tabsir.net/?p=633#more-633 |url-status=live }}</ref> Each month still has either 29 or 30 days, but due to the variable method of observations employed, there is usually no discernible order in the sequencing of either 29 or 30-day month lengths. Traditionally, the first day of each month is the day (beginning at sunset) of the first sighting of the ''hilal'' (crescent moon) shortly after sunset. If the ''hilal'' is not observed immediately after the 29th day of a month (either because clouds block its view or because the western sky is still too bright when the moon sets), then the day that begins at that sunset is the 30th. Such a sighting has to be made by one or more trustworthy men testifying before a committee of Muslim leaders. Determining the most likely day that the ''hilal'' could be observed was a motivation for Muslim interest in astronomy, which put Islam in the forefront of that science for many centuries. Still, due to the fact that both lunar reckoning systems are ultimately based on the lunar cycle itself, both systems still do roughly correspond to one another, never being more than three days out of synchronisation with one another.
[[File:استهلال ماه رمضان در شهر قم، عکاس مصطفی معراجی، بلندی های بوستان علوی قم 12.jpg|alt=One man watches another, who looks through a modern telescope|thumb|Muslim clerics observe the moon.]]

This traditional practice for the determination of the start-date of the month is still followed in the overwhelming majority of Muslim countries. For instance, [[Saudi Arabia]] uses the sighting method to determine the beginning of each month of the Hijri calendar. Since AH 1419 (1998/99), several official ''hilal'' sighting committees have been set up by the government to determine the first visual sighting of the lunar crescent at the beginning of each lunar month. Nevertheless, the religious authorities also allow the testimony of less experienced observers and thus often announce the sighting of the lunar crescent on a date when none of the official committees could see it.

Each Islamic state proceeds with its own monthly observation of the new moon (or, failing that, awaits the completion of 30 days) before declaring the beginning of a new month on its territory. However, the lunar crescent becomes visible only some 17 hours after the conjunction, and only subject to the existence of a number of favourable conditions relative to weather, time, geographic location, as well as various astronomical parameters.<ref>Karim Meziane et [[Nidhal Guessoum]]: La visibilité du croissant lunaire et le ramadan, La Recherche n° 316, janvier 1999, pp. 66–71.</ref> Given the fact that the moon sets progressively later than the sun as one goes west, with a corresponding increase in its "age" since conjunction, Western Muslim countries may, under favorable conditions, observe the new moon one day earlier than eastern Muslim countries. Due to the interplay of all these factors, the beginning of each month differs from one Muslim country to another, during the 48-hour period following the conjunction. The information provided by the calendar in any country does not extend beyond the current month.

A number of Muslim countries try to overcome some of these difficulties by applying different astronomy-related rules to determine the beginning of months. Thus, [[Malaysia]], [[Indonesia]], and a few others begin each month at sunset on the first day that the moon sets after the sun (moonset after sunset). In Egypt, the month begins at sunset on the first day that the moon sets at least five minutes after the sun. A detailed analysis of the available data shows, however, that there are major discrepancies between what countries say they do on this subject, and what they actually do. In some instances, what a country says it does is impossible.<ref>{{cite web|url=http://www.moonsighting.com/calculation-or-sighting.html|title=Calculations or Sighting for starting an Islamic month|website=www.moonsighting.com|access-date=16 April 2017|archive-url=https://web.archive.org/web/20170508214424/http://www.moonsighting.com/calculation-or-sighting.html|archive-date=8 May 2017|url-status=dead}}</ref><ref>{{cite web|url=http://oumma.com/Le-mois-islamique-est-il-universel|title=Le mois islamique est-il universel ou national ?|author=Oumma|date=23 June 2010|work=Oumma|access-date=20 September 2010|archive-date=5 October 2016|archive-url=https://web.archive.org/web/20161005080558/http://oumma.com/Le-mois-islamique-est-il-universel|url-status=live}}</ref>

Due to the somewhat variable nature of the Islamic calendar, in most Muslim countries, the Islamic calendar is used primarily for religious purposes, while the Solar-based Gregorian calendar is still used primarily for matters of [[commerce]] and [[agriculture]].

==Theological considerations==
If the Islamic calendar were prepared using astronomical calculations, Muslims throughout the Muslim world could use it to meet all their needs, the way they use the Gregorian calendar today. But, there are divergent views on whether it is licit to do so.<ref>Allal el Fassi : "Aljawab assahih wannass-hi al-khaliss 'an nazilati fas wama yata’allaqo bimabda-i acchouhouri al-islamiyati al-arabiyah", "[...] and the beginning of Islamic Arab months", report prepared at the request of King Hassan II of Morocco, Rabat, 1965 (36 p.), with no indication of editor.</ref>

A majority of theologians oppose the use of calculations (beyond the constraint that each month must be not less than 29 nor more than 30 days) on the grounds that the latter would not conform with Muhammad's recommendation to observe the new moon of Ramadan and Shawal in order to determine the beginning of these months.<ref>{{cite book|first=Muhammad Mutawalli |last= al-Shaârawi |title=Fiqh al-halal wal haram |editor=Ahmad Azzaâbi |location= Dar al-Qalam, Beyrouth |date=2000 |page=88}}</ref>{{efn|Some theologians also interpret ''Surah al-Baqarah'' 2:185 as requiring direct sighting, but they represent only a minority. The Quranic verse reads as follows : "The month of Ramadân in which was revealed the Qur'ân, a guidance for mankind and clear proofs for the guidance and the criterion (between right and wrong). So whoever of you sights (the crescent on the first night of) the month (of Ramadân i.e., is present at his home), he must observe Saum (fasts) that month, and whoever is ill or on a journey, the same number [of days which one did not observe ''Saum'' (fasts) must be made up] from other days. God intends for you ease, and He does not want to make things difficult for you. (He wants that you) must complete the same number (of days), and that you must magnify God [i.e., to say ''Takbîr'' ("''Allāhu-Akbar''", [i.e.] "God is the Most Great") on seeing the crescent of the months of Ramadân and Shawwâl] for having guided you so that you may be grateful to Him."- {{Qref|2|185|b=yl|t=nq}}.}}

However, some [[Ulama|Islamic jurists]] see no contradiction between Muhammad's teachings and the use of calculations to determine the beginnings of lunar months.<ref>{{cite web |url=http://www.islamonline.net/Arabic/contemporary/2003/10/article03.shtml |author=Abderrahman al-Haj |title=لماذا الاختلاف حول الحساب الفلكي؟ |trans-title=Why the difference about the astronomical calculation? |language=ar |date=2003 |access-date=13 June 2008 |archive-date=30 April 2008 |archive-url=https://web.archive.org/web/20080430021006/http://www.islamonline.net/arabic/contemporary/2003/10/article03.shtml |url-status=live }}</ref> They consider that Muhammad's recommendation was adapted to the culture of the times, and should not be confused with the acts of worship.<ref>Allal el Fassi : "Aljawab assahih..." op. cit.</ref>{{efn|The dynasty of Fatimids in Egypt used a tabular pre-calculated calendar over a period of two centuries, between the 10th and 12th centuries, before a change of political regime reactivated the procedure of observation of the new moon.}}<ref>{{cite web|url=http://www.math.nus.edu.sg/aslaksen/calendar/islamic.html|title=The Islamic Calendar|access-date=13 June 2008|archive-date=26 May 2008|archive-url=https://web.archive.org/web/20080526130731/http://www.math.nus.edu.sg/aslaksen/calendar/islamic.html|url-status=live}}</ref>

Thus the jurists [[Ahmad Muhammad Shakir]] and [[Yusuf al-Qaradawi]] both endorsed the use of calculations to determine the beginning of all months of the Islamic calendar, in 1939 and 2004 respectively.<ref>{{cite web 
|url=http://ahmadmuhammadshakir.blogspot.com/ 
|title=أوائل الشهور العربية .. هل يجوز شرعاً إثباتها 
|trans-title=The beginning of the Arab months..is it permissible according to Islamic law? 
|access-date=13 June 2008 
|archive-date=8 July 2011 
|archive-url=https://web.archive.org/web/20110708022230/http://ahmadmuhammadshakir.blogspot.com/ 
|url-status=live 
}}</ref><ref>For a detailed discussion of Shakir's legal opinion on the subject, see "Issue N° 9" in [http://tabsir.net/?p=633#more-633 Khalid Chraibi: Issues in the Islamic Calendar, Tabsir.net] {{Webarchive|url=https://web.archive.org/web/20081006083025/http://tabsir.net/?p=633#more-633 |date=6 October 2008 }}</ref> So did the [[Fiqh Council of North America]] (FCNA) in 2006<ref>{{cite web|url=http://www.fiqhcouncil.org/Default.aspx?tabid=55|title=Fiqh Council of North America Islamic lunar calendar|url-status=dead|archive-url=https://web.archive.org/web/20080516105409/http://www.fiqhcouncil.org/Default.aspx?tabid=55|archive-date=16 May 2008}}</ref><ref>{{cite web|url=http://www.icbwayland.org/include/CalculationsFiqhPosition.pdf|title=Zulfikar Ali Shah The astronomical calculations: a fiqhi discussion|url-status=dead|archive-url=https://web.archive.org/web/20080809032701/http://www.icbwayland.org/include/CalculationsFiqhPosition.pdf|archive-date=9 August 2008}}</ref> and the [[European Council for Fatwa and Research]] (ECFR) in 2007.<ref>{{cite web|url=http://www.icbwayland.org/include/MoonsightingDecisionWeb.pdf|title=Islamic Center of Boston, Wayland|access-date=11 July 2008|archive-date=9 August 2008|archive-url=https://web.archive.org/web/20080809032655/http://www.icbwayland.org/include/MoonsightingDecisionWeb.pdf|url-status=live}}</ref><ref>For a detailed discussion of the issues and the FCNA and ECFR positions, see : [http://tabsir.net/?p=621#more-621 Khalid Chraibi: Can the Umm al Qura calendar serve as a global Islamic calendar? Tabsir.net] {{Webarchive|url=https://web.archive.org/web/20081206144650/http://tabsir.net/?p=621#more-621 |date=6 December 2008 }}</ref>

The major Muslim associations of France also announced in 2012 that they would henceforth use a calendar based on astronomical calculations, taking into account the criteria of the possibility of crescent sighting in any place on Earth.<ref>{{cite web|url=http://oumma.com/13434/ramadan-moubarak|last=Oumma|title=Le Conseil Français du Culte Musulman (CFCM): Ramadan moubarak!|date=19 July 2012|access-date=15 January 2019|archive-date=3 March 2016|archive-url=https://web.archive.org/web/20160303204916/http://oumma.com/13434/ramadan-moubarak|url-status=live}}</ref><ref>{{cite web|url=http://oummatv.tv/13306/sera-premier-jour-mois-de-ramadan|last=Nidhal Guessoum|title=Quel sera le premier jour du mois de Ramadan 2012? (On which date will Ramadan 2012 begin?)|date=5 July 2012|access-date=15 January 2019|archive-date=28 September 2018|archive-url=https://web.archive.org/web/20180928122502/http://oummatv.tv/13306/sera-premier-jour-mois-de-ramadan|url-status=live}}</ref> But, shortly after the official adoption of this rule by the [[French Council of the Muslim Faith]] (CFCM) in 2013, the new leadership of the association decided, on the eve of Ramadan 2013, to follow the Saudi announcement rather than to apply the rule just adopted. This resulted in a division of the Muslim community of France, with some members following the new rule, and others following the Saudi announcement.

Isma'ili-Taiyebi Bohras having the institution of ''[[Da'i al-Mutlaq|da'i al-mutlaq]]'' follow the tabular Islamic calendar (see section below) prepared on the basis of astronomical calculations from the days of [[Fatimid Caliphate|Fatimid]] [[imam]]s.

==Calculated Islamic calendars==
===Islamic calendar of Turkey===
Turkish Muslims use an Islamic calendar which is calculated several years in advance by the [[Presidency of Religious Affairs|Turkish Presidency of Religious Affairs]] (Diyanet İşleri Başkanlığı). From 1 Muharrem 1400 AH (21 November 1979) until 29 Zilhicce 1435 (24 October 2014) the computed Turkish lunar calendar was based on the following rule: "The lunar month is assumed to begin on the evening when, within some region of the terrestrial globe, the computed centre of the lunar crescent at local sunset is more than 5° above the local horizon and (geocentrically) more than 8° from the Sun." In the current rule the (computed) lunar crescent has to be above the local horizon of [[Ankara]] at sunset.<ref name=turkey>{{cite web |url=https://webspace.science.uu.nl/~gent0113/islam/diyanetcalendar.htm |title=The Islamic Calendar of Turkey |work=[[Mathematical Institute]] |publisher=[[Utrecht University]] |access-date=4 February 2021 |date=April 2021 |first=R.H. |last=van Gent |archive-date=31 January 2021 |archive-url=https://web.archive.org/web/20210131000244/https://webspace.science.uu.nl/~gent0113/islam/diyanetcalendar.htm |url-status=live }}</ref>

===Saudi Arabia's ''Umm al-Qura'' calendar===
Saudi Arabia has traditionally used the Umm al-Qura calendar, which is based on astronomical calculations, for administrative purposes. The parameters used in the establishment of this calendar underwent significant changes during the decade to AH 1423.<ref>{{cite web |url=http://www.icoproject.org/pdf/khan_2001.pdf |title=Crescent sighting using the Uml al Qura calendar in Saudi Arabia To Determine Ramadan And Eid Ul Fitir Of 1422 AH And Its Implications For Unity In Different Countries By Dr. Muhammad M H Khan |archive-url=https://web.archive.org/web/20060515093842/http://www.icoproject.org/pdf/khan_2001.pdf |archive-date=15 May 2006 |year=2001 |access-date=4 February 2022 |work=Ico Project}}</ref><ref>{{cite web |url=https://webspace.science.uu.nl/~gent0113/islam/ummalqura.htm |title=The Umm al-Qura Calendar of Saudi Arabia |work=[[Mathematical Institute]] |publisher=[[Utrecht University]] |first=R.H. |last=van Gent |date=April 2021 |access-date=4 February 2022 |archive-date=11 June 2011 |archive-url=https://web.archive.org/web/20110611040922/http://www.staff.science.uu.nl/~gent0113/islam/ummalqura.htm |url-status=live }}</ref>

Before AH 1420 (before 18 April 1999), if the moon's age at sunset in [[Riyadh]] was at least 12 hours, then the day ''ending'' at that sunset was the first day of the month. This often caused the Saudis to celebrate holy days one or even two days before other predominantly Muslim countries, including the dates for the Hajj, which can only be dated using Saudi dates because it is performed in Mecca.

From AH 1420–22, if moonset occurred after sunset at Mecca, then the day beginning at that sunset was the first day of a Saudi month, essentially the same rule used by Malaysia, Indonesia, and others (except for the location from which the ''hilal'' was observed).

Since the beginning of AH 1423 (16 March 2002), the rule has been clarified a little by requiring the geocentric conjunction of the sun and moon to occur before sunset, in addition to requiring moonset to occur after sunset at Mecca. This ensures that the moon has moved past the sun by sunset, even though the sky may still be too bright immediately before moonset to actually see the crescent.

In 2007, the [[Islamic Society of North America]], the ''Fiqh'' Council of North America and the European Council for ''[[Fatwa]]'' and Research announced that they would henceforth use a calendar based on calculations using the same parameters as the ''Umm al-Qura'' calendar to determine (well in advance) the beginning of all lunar months (and therefore the days associated with all religious observances). This was intended as a first step on the way to unify, at some future time, Muslims' calendars throughout the world.<ref>{{cite web |url=http://tabsir.net/?p=621#more-621 |website=tabsir.net |title=Can the Umm al Qura calendar serve as a global Islamic calendar? |first=Khalid |last=Chraibi |date=23 July 2008 |access-date=4 February 2022 |publisher=[[WordPress]] |archive-date=8 March 2022 |archive-url=https://web.archive.org/web/20220308190450/http://tabsir.net/?p=621#more-621 |url-status=live }}</ref>

On 14 February 2016, Saudi Arabia [[adoption of the Gregorian calendar|adopted the Gregorian calendar]] for payment of the monthly salaries of government employees (as a cost cutting measure),<ref>{{cite news |url=https://www.dw.com/en/saudi-arabia-switches-to-western-calendar/a-35942460 |title=Saudi Arabia trims expenses and work days |date=10 February 2016 |access-date=15 January 2023 |work=[[DW News]] |publisher=[[Deutsche Welle]] |archive-date=16 January 2023 |archive-url=https://web.archive.org/web/20230116104948/https://www.dw.com/en/saudi-arabia-switches-to-western-calendar/a-35942460 |url-status=live }}</ref> while retaining the Islamic calendar for religious purposes.<ref name=Economist171216>{{cite news |url=https://www.economist.com/news/middle-east-and-africa/21711938-hauling-saudi-arabia-21st-century-saudi-arabia-adopts-gregorian |title=The prince's time machine: Saudi Arabia adopts the Gregorian calendar |newspaper=[[The Economist]] |date=17 December 2016 |access-date=4 February 2022 |publisher=[[The Economist Newspaper Limited]] |archive-date=14 October 2017 |archive-url=https://web.archive.org/web/20171014042857/https://www.economist.com/news/middle-east-and-africa/21711938-hauling-saudi-arabia-21st-century-saudi-arabia-adopts-gregorian |url-status=live }}</ref>

==Other calendars using the Islamic era==
The [[Solar Hijri calendar]] is a solar calendar used in Iran which counts its years from the [[Hijra (Islam)|Hijra]] or migration of Muhammad from Mecca to Medina in 622 CE.<ref>{{cite book|page=[https://books.google.com/books?id=Yxd3E-_AqSEC&q=shah+calendar+change&pg=PA13 13]|title=Persian Pilgrimages by Afshin Molavi |isbn=978-0-393-05119-3 |last1=Molavi |first1=Afshin |last2=Mawlawī |first2=Afšīn |year=2002 |publisher=W. W. Norton & Company }}</ref>

==Tabular Islamic calendar==
{{Main|Tabular Islamic calendar}}
The Tabular Islamic calendar is a rule-based variation of the Islamic calendar, in which months are worked out by arithmetic rules rather than by observation or astronomical calculation. It has a 30-year cycle with 11 [[leap year]]s of 355 days and 19 years of 354 days. In the long term, it is accurate to one day in about 2,500 solar years or 2,570 lunar years. It also deviates up to about one or two days in the short term.

===Kuwaiti algorithm===
[[Microsoft]] uses the "Kuwaiti algorithm", a variant of the tabular Islamic calendar,<ref>[https://webspace.science.uu.nl/~gent0113/islam/islam_tabcal.htm#kuwait The "Kuwaiti Algorithm"] {{Webarchive|url=https://web.archive.org/web/20220723011404/https://webspace.science.uu.nl/~gent0113/islam/islam_tabcal.htm#kuwait |date=23 July 2022 }} (Robert van Gent).</ref> to convert Gregorian dates to the Islamic ones. Microsoft claimed that the variant is based on a statistical analysis of historical data from [[Kuwait]], however it matches a known tabular calendar.

==Notable dates==
{{Main|Muslim holidays}}
Important dates in the Islamic (Hijri) year are:
* 1 Muharram: the [[Islamic New Year]].
* 10 Muharram: [[Day of Ashura]]. For both Shias and Sunnis, the martyrdom of [[Husayn ibn Ali]], the grandson of Muhammad, and his followers. For Sunnis, the crossing of the [[Red Sea]] by [[Islamic view of Moses|Moses]] occurred on this day, along with many other significant events in the [[Prophets and messengers in Islam|lives of prophets]] and that have to do with [[Creationism|Creation]].<ref>{{Cite web |title=What are the Events That Happened on the Day of Ashura? – Ask a Question to Us |url=http://askaquestionto.us/question-answer/the-day-of-ashura/what-are-the-events-that-happened-on-the-day-of-ashura |access-date=2022-07-31 |website=askaquestionto.us |archive-date=31 July 2022 |archive-url=https://web.archive.org/web/20220731022524/http://askaquestionto.us/question-answer/the-day-of-ashura/what-are-the-events-that-happened-on-the-day-of-ashura |url-status=live }}</ref>
* 12 Rabi al-Awwal: [[Mawlid]] or Birth of the Prophet for Sunnis.
* 17 Rabi al-Awwal: [[Mawlid]] for Shias.
* 27 Rajab: [[Isra and Mi'raj]] for the majority of Muslims.
* 15 Sha'ban: [[Mid-Sha'ban]], or Night of Forgiveness. For Shiites, also the birthday of [[Muhammad al-Mahdi]], the Twelfth Imam.
* 1 Ramadan: The first day of [[fasting in Islam]]
* 27 Ramadan: Start of the [[Waḥy|Revelation of the Qur’an]]. The most probable day Muhammad received the first verses of the [[Quran]] (17 Ramadan in Indonesia and Malaysia).
* Last third of Ramadan which includes [[Laylat al-Qadr]].
* Last Friday of Ramadan: [[Jumu'atul-Wida]]
* 1 Shawwal: [[Eid ul-Fitr]].
* 8–13 Dhu al-Hijjah: The [[Hajj]] pilgrimage to Mecca.
* 9 Dhu al-Hijjah: [[Day of Arafa]].
* 10 Dhu al-Hijjah: [[Eid al-Adha]].

Days considered important predominantly for Shia Muslims:
* 9 Rabi' al-Awwal: [[Omar Koshan]] ([[Mukhtar al-Thaqafi]] avenges the events of [[Ashura]]).
* [[13 Rajab]]: Birthday of [[Ali|Ali ibn Abi Talib]]
* 3 Sha'ban: Birthday of [[Husayn ibn Ali]].
* [[21 Ramadan]]: Martyrdom of [[Ali|Ali ibn Abi Talib]].
* 18 Dhu al-Hijjah: the [[Eid al-Ghadir]]

==Uses==
[[File:Inscription of years by A.H.&A.D. eras.jpg|thumb|250px|Civil and Hijri establishment dates of a library in Old City, Jerusalem]]
The Islamic calendar is now used primarily for religious purposes, and for official dating of public events and documents in Muslim countries. Because of its nature as a purely lunar calendar, it cannot be used for agricultural purposes and historically Islamic communities have used other calendars for this purpose: the [[Egyptian calendar]] was formerly widespread in Islamic countries, and the [[Iranian calendars|Iranian calendar]], the [[Tarikh-e-Elahi|Akbar's calendar]] (from where the [[Bengali calendar]] originated),<ref>{{cite book |author1=Kunal Chakrabarti |author2=Shubhra Chakrabarti |title=Historical Dictionary of the Bengalis |url=https://books.google.com/books?id=QVOFAAAAQBAJ&pg=PA114 |year=2013 |publisher=Scarecrow |isbn=978-0-8108-8024-5 |pages=114–115 |access-date=11 October 2024 |archive-date=15 April 2023 |archive-url=https://web.archive.org/web/20230415073820/https://books.google.com/books?id=QVOFAAAAQBAJ&pg=PA114 |url-status=live}}</ref><ref>{{Cite encyclopedia |year=2015 |title=Pahela Baishakh |encyclopedia=Banglapedia |publisher=Asiatic Society of Bangladesh |location=Dhaka, Bangladesh |url=http://en.banglapedia.org/index.php?title=Pahela_Baishakh |access-date=11 October 2024 |archive-date=7 September 2019 |archive-url=https://web.archive.org/web/20190907065950/http://en.banglapedia.org/index.php?title=Pahela_Baishakh |url-status=live}}</ref> the 1789 [[Rumi calendar|Ottoman calendar]] (a modified [[Julian calendar]]) were also used for agriculture in their countries.{{citation needed|date=May 2016}} In the [[Levant]] and [[Iraq]] the [[Arabic names of Gregorian months#Iraq and the Levant|Aramaic names of the Babylonian calendar]] are still used for all secular matters. In the [[Maghreb]], Berber farmers in the countryside still use the Julian calendar for agrarian purposes.<ref name="EB">{{cite journal |last1=Gast |first1=M. |last2=Delheur |first2=J. |last3=E.B. |title=Calendrier |url=http://journals.openedition.org/encyclopedieberbere/2039 |journal=Encyclopédie Berbère |year=1992 |issue=11 |pages=1713–1720 |publisher=OpenEdition |doi=10.4000/encyclopedieberbere.2039 |access-date=5 July 2018 |language=fr |doi-access=free |archive-date=6 July 2018 |archive-url=https://web.archive.org/web/20180706022747/https://journals.openedition.org/encyclopedieberbere/2039 |url-status=live }}</ref> These local solar calendars have receded in importance with the near-universal adoption of the Gregorian calendar for civil purposes.{{citation needed|date=May 2016}} Saudi Arabia uses the lunar Islamic calendar.{{efn|The start of each lunar month determined not ahead of time by astronomical calculation, but only after the crescent moon is sighted by the proper religious authorities.<ref>[[#HT2009|Tripp, ''Culture Shock'', 2009]]: pp. 154–5).</ref>}} In Indonesia, the [[Javanese calendar]] combines elements of the Islamic and pre-Islamic [[Indian national calendar|Saka]] calendars.{{citation needed|date=May 2016}}

British author [[Nicholas Hagger]] writes that after seizing control of [[Libya]], [[Muammar Gaddafi]] "declared" on 1 December 1978 "that the Muslim calendar should start with the death of the prophet Mohammed in 632 rather than the hijra (Mohammed's 'emigration' from Mecca to Medina) in 622". This put the country ten solar years behind the standard Muslim calendar.<ref>{{cite book |last=Hagger |first=Nicholas |title=The Libyan Revolution: Its Origins and Legacy |year=2009 |publisher=O Books |location=Winchester, UK |pages=109}}</ref> However, according to the 2006 ''Encyclopedia of the Developing World'', "More confusing still is Qaddafi's unique Libyan calendar, which counts the years from the Prophet's birth, or sometimes from his death. The months July and August, named after [[Julius Caesar|Julius]] and [[Augustus]] Caesar, are now [[Gamal Abdel Nasser|Nasser]] and [[Hannibal]] respectively."<ref>''Encyclopedia of the Developing World'' (2007), volume 3, p. 1338.</ref> Reflecting on a 2001 visit to the country, American reporter [[Neil MacFarquhar]] observed, "Life in Libya was so unpredictable that people weren't even sure what year it was. The year of my visit was officially 1369. But just two years earlier Libyans had been living through 1429. No one could quite name for me the day the count changed, especially since both remained in play.&nbsp;... Event organizers threw up their hands and put the Western year in parentheses somewhere in their announcements."<ref name="MacFarquhar2010">{{cite book|author=Neil MacFarquhar|title=The Media Relations Department of Hizbollah Wishes You a Happy Birthday: Unexpected Encounters in the Changing Middle East|url={{Google books|gzQBfS5nkiAC|page=PA38|keywords=|text=|plainurl=yes}}|year=2010|publisher=ReadHowYouWant|isbn=978-1-4587-6009-8}} pages 37–38.</ref>

==Computer support==
* Hijri support was available in later versions of traditional [[Visual Basic (classic)|Visual Basic]], and is also available in the [[.NET Framework]].
* Since the release of [[Java 8]], the Islamic calendar is supported in the new Date and Time API.

==See also==
* [[Arabic names of Gregorian months]]
* [[Islamic New Year]] – Includes a table of recent and imminent equivalent dates in the Gregorian calendar
* [[List of Islamic years]] – Most significant dates have both the Hijri date and the Gregorian date
<!-- Please do not add other calendars here as they are all in the {{calendars}} template below. Any that are particularly relevant will surely have been mentioned already in the body of the article. -->
* [[List of observances set by the Islamic calendar]]
* [[Pre-Islamic Arabian calendar]]
* {{anl|Rumi calendar}}
* {{anl|Solar Hijri calendar}}
* [[Timeline of Islamic history]] – Including a list of Islamic centuries and the corresponding Gregorian years

==Notes==
{{notelist}}

==References==
{{Citation style|date=August 2022}}
{{reflist}}

==External links==
*{{cite Americana|short=1|wstitle=Hegira}}
*[https://aau.ac.ae/en/blog/how-and-why-did-the-hijiri-calendar-begin#:~:text=The%20Hijri%20year%20consists%20of%2012%20months%3A%20Muharram%2C%20Safar%2C,da%20and%20Dhu%20Al%20Hijja. How and Why did the Hijiri Calendar Begin?] – ''Al-Ain University''
*[https://web.archive.org/web/20181222152856/http://www.math.nus.edu.sg/aslaksen/calendar/islamic.shtml#Rules Helmer Aslaksen The Islamic Calendar] (archived)
*[https://sagateller.com/living-a-devotional-sufi-life-with-islamic-calendar/ Living a Devotional Sufi Life with Islamic Calendar] 
*[http://tabsir.net/?p=1901 Khalid Chraibi, The reform of the Islamic calendar: the terms of the debate]. ''Tabsir.net''. September 2012.
*{{cite EB1911 |wstitle=Calendar/Mahommedan Calendar |display=Mahommedan Calendar |volume=4 |pages=1001–1003 |short=1}}

===Open source calendar converters===
{{hatnote|Calendar converters typically rely on the [[tabular Islamic calendar]] given the lack of a precise record of lunar observations.}}
*{{cite web |title=Calendar Converter for Near East Historians |url=https://www.muqawwim.com/ | first=T.S. |last=Beers |date=2018 |website=muqawwim.com}}
*{{cite web|title=Calendar converter |url=https://www.fourmilab.ch/documents/calendar/ |first=John |last=Walker |author-link=John Walker (programmer) |website=fourmilab.ch |date=September 2015}}

{{IslamicMonths}}
{{Time topics}}
{{Islamic astronomy}}
{{Islam topics |collapsed}}
{{Time measurement and standards}}
{{Calendars}}
{{Chronology}}
{{Characters and names in the Quran}}

{{Authority control}}

{{DEFAULTSORT:Islamic Calendar}}
[[Category:Islamic calendar| ]]
[[Category:Islamic terminology|Calendar]]
[[Category:Arab inventions]]