View source for ExFAT

{{Short description|Flash file system}}
{{lowercase}}
{{Infobox filesystem
| name = exFAT
| developer = [[Microsoft]]
| full_name = Extensible File Allocation Table
| introduction_date = {{Start date and age|2006|11}}
| introduction_os = [[Windows Embedded CE 6.0]]
| partition_id = {{plainlist|
*[[Master Boot Record|MBR]]/[[Extended Boot Record|EBR]]: {{mono|[[Partition type#PID_07h|0x07]]}} <small>(same as for [[High Performance File System|HPFS]]/[[NTFS]])</small>
*[[Basic Data Partition|BDP]]/[[GUID Partition Table|GPT]]: {{mono|EBD0A0A2-B9E5-4433-87C0-68B6B72699C7}}}}
| directory_struct = Table
| file_struct = [[bit array|bitmap]], [[linked list]]
| bad_blocks_struct = Cluster tagging
| max_volume_size = 128&nbsp;[[petabyte|PB]], 512&nbsp;[[terabyte|TB]]&nbsp;recommended<ref name="xpkb" /><ref group="nb" name="NB_Size_Volume" />
| max_file_size = 128 PB<ref group="nb" name="NB_Size_File" />
| max_files_no = up to 2,796,202 per directory<ref name="uspatent" />
| max_filename_size = 255 characters
| filename_character_set = all [[List of Unicode characters|Unicode characters]] except {{nowrap|U+0000 ([[null character|NUL]])}} to {{nowrap|U+001F ([[Unit separator|US]])}} {{nowrap|<code>/</code> ([[Slash (punctuation)|slash]])}} {{nowrap|<code>\</code> ([[backslash]])}} {{nowrap|<code>:</code> ([[Colon (punctuation)|colon]])}} {{nowrap|<code>*</code> ([[asterisk]])}} {{nowrap|<code>?</code> ([[question mark]])}} {{nowrap|<code>"</code> ([[Quotation mark|quote]])}} {{nowrap|<code>&lt;</code> ([[Bracket|less than]])}} {{nowrap|<code>&gt;</code> ([[Bracket|greater than]])}} and {{nowrap|<code>&#124;</code> ([[Vertical bar|pipe]])}}<br>(encoding in [[UTF-16|UTF-16LE]]){{cn|date=February 2023}}
| dates_recorded = Creation, last modified, last access
| date_range = 1980-01-01 to 2107-12-31
| date_resolution = {{ubli
 | 10&nbsp;ms for last modified time,
 | 10&nbsp;ms for creation time,
 | 2&nbsp;seconds day for access date
 }}
| forks_streams = No
| attributes = Read-only, hidden, system, subdirectory, archive
| file_system_permissions = [[Access-control list|ACL]] (Windows CE 6 only)
| compression = No
| encryption = Yes, [[Encrypting File System|EFS]] supported in Windows 10 v1607 and Windows Server 2016 or later.
| OS = {{plainlist|
*[[Windows Embedded CE 6.0]]
*[[Windows XP SP2]]<ref name="xpkb" /> and later
*[[Windows Server 2003 SP2]]<ref name="xpkb" /> and later
*[[Linux distros]] with either [[Linux kernel]] v5.4+<ref>{{Cite web|url=https://lwn.net/Articles/805462/|title=The 5.4 kernel has been released|author=corbet|date=2019-11-25|website=LWN.net|access-date=2019-12-01}}</ref> or [[Filesystem in Userspace|FUSE]]<ref name="exfat-fuse" />
*[[FreeBSD]] with [[Filesystem in Userspace|FUSE]]<ref>{{Cite web|url=https://man.freebsd.org/cgi/man.cgi?query=mount.exfat-fuse&apropos=0&sektion=8&manpath=FreeBSD+14.1-RELEASE+and+Ports&arch=default&format=html|title=mount.exFAT map page from FreeBSD ports|author=Andrew Nayenko|date=2015-11-12|language=en|access-date=2024-10-12}}</ref>
*[[Mac OS X 10.6]] and later<ref>{{Cite web|url=https://www.macrumors.com/2010/11/11/mac-os-x-10-6-5-notes-exfat-support-airprint-flash-player-vulnerability-fixes/|title=Mac OS X 10.6.5 Notes: exFAT Support, AirPrint, Flash Player Vulnerability Fixes|language=en|author=Eric Slivka|date=2010-11-11|website=MacRumors|access-date=2023-12-26}}</ref> 
*[[Android 13]] and some devices running previous versions
*[[iOS 13.1]] and later
*[[ChromeOS]]
}}
| variants = 
| data_deduplication = 
}}

'''exFAT''' ('''Extensible File Allocation Table''') is a [[file system]] optimized for [[flash memory]] such as [[USB flash drive]]s and [[Secure Digital|SD cards]], that was introduced by [[Microsoft]] in 2006.<ref name="flash-format" /> exFAT was [[Proprietary format|proprietary]] until 28 August 2019, when Microsoft published its specification.<ref name="exfatspec">{{Cite web|url=https://docs.microsoft.com/en-us/windows/win32/fileio/exfat-specification|title=exFAT Specification|author=Microsoft|date=August 28, 2019|url-status=live|archive-url=https://web.archive.org/web/20200719152933/https://docs.microsoft.com/en-us/windows/win32/fileio/exfat-specification|archive-date=2020-07-19}}</ref> Microsoft owns [[Patent|patents]] on several elements of its design.<ref name="uspatent" />

exFAT can be used where [[NTFS]] is not a feasible solution (due to data-structure overhead), but where a greater [[large file support|file-size limit]] than that of the standard [[FAT32]] file system (i.e. 4&nbsp;[[gigabyte|GB]]) is required.

exFAT has been adopted by the [[SD Association]] as the default file system for [[SDXC]] and [[SDUC]] cards larger than 32&nbsp;[[Gigabyte|GB]].

Windows 8 and later versions natively support exFAT boot, and support the installation of the system in a special way to run in the exFAT volume.

== History ==
exFAT was introduced in late 2006 as part of [[Windows CE 6.0]], an embedded Windows operating system. Support was added to regular Windows with [[Windows Vista Service Pack 1]] and [[Windows Server 2008]], both released on February 4, 2008. An update for [[Windows XP]] and [[Windows Server 2003]] was later released.

Most of the vendors signing on for licenses are manufacturers of embedded systems or device manufacturers that produce media formatted with exFAT. The entire [[File Allocation Table]] (FAT) family, exFAT included, is used for embedded systems because it is lightweight and is better suited for solutions that have low memory and low power requirements, and can be easily implemented in [[firmware]].

== Features ==

Because file size references are stored in eight instead of four bytes, the [[Large file support|file size limit]] has increased to {{nowrap|16 [[exabyte]]s (EB)}} ({{nowrap|2<sup>64</sup> − 1 bytes}}, or about {{nowrap|10<sup>19</sup> bytes}}, which is otherwise limited by a maximum volume size of {{nowrap|128 [[petabyte|PB]],<ref group="nb" name="NB_Size_File" />}} or {{nowrap|2<sup>57</sup> − 1 bytes}}), raised from {{nowrap|4 [[gigabyte|GB]]}} ({{nowrap|2<sup>32</sup> − 1 bytes}}) in a standard FAT32 file system.<ref name="xpkb" /> Therefore, for the typical user, this enables seamless [[interoperability]] between Windows, [[Linux]] and {{nowrap|macOS}} platforms for files in excess of 4&nbsp;GB.

Other specifications, features, and requirements of the exFAT file system include:
* Scalability to large disk sizes: about 128&nbsp;[[Petabyte|PB]] ({{nowrap|2<sup>57</sup> − 1 bytes}})<ref>{{cite web |url=http://msdn.microsoft.com/en-us/library/windows/desktop/ee681827(v=vs.85).aspx |title=File System Functionality Comparison |publisher=Microsoft |access-date=February 26, 2015 |archive-date=April 7, 2015 |archive-url=https://web.archive.org/web/20150407044554/https://msdn.microsoft.com/en-us/library/windows/desktop/ee681827(v=vs.85).aspx |url-status=live}}.</ref><ref group="nb" name="NB_Size_Volume" /> maximum, 512&nbsp;[[Terabyte|TB]] ({{nowrap|2<sup>49</sup> − 1 bytes}}) recommended maximum, raised from the 32-bit limit (2&nbsp;TB for a sector size of 512&nbsp;bytes) of standard FAT32 partitions.<ref>{{cite web | url=http://support.microsoft.com/kb/314463 | title=Limitations of the FAT32 File System in Windows XP | access-date=February 11, 2011 | date=December 1, 2007 | publisher=Microsoft | archive-date=February 24, 2015 | archive-url=https://web.archive.org/web/20150224162047/http://support.microsoft.com/kb/314463 | url-status=live }}</ref>
* Support for up to 2,796,202 files per [[Folder (computing)|directory]].<ref name="uspatent" /><ref group="nb" name="NB_Count_Files" /> Microsoft documents a limit of 65,534 (2<sup>16</sup>&nbsp;−&nbsp;2) files per sub-directory for their FAT32 implementation, but other operating systems have no special limit for the number of files in a FAT32 directory. FAT32 implementations in other operating systems allow an unlimited number of files up to the number of available clusters (that is, up to 268,304,373 files on volumes without [[long filenames]]).<ref group="nb" name="NB_NUM-CLUST" />
* Maximum number of files on volume C{{clarify|date=April 2022}}, to 4,294,967,285 ({{nowrap|2{{sup|32}} − 11}}, up from about {{nowrap|2{{sup|28}} − 11<ref group="nb" name="NB_NUM-CLUST" />}} in standard FAT32).
* Free space allocation and delete performance improved due to introduction of a [[free-space bitmap]].
* Timestamp granularity of 10&nbsp;[[millisecond|ms]] for creation and modified times (down from 2&nbsp;s on FAT, but not as fine as NTFS's 100&nbsp;ns).<ref name="uspatent" />
* Timestamp granularity for last-access time to double seconds (FAT had date only).
* Timestamps come with a [[time zone]] marker in offset relative to [[UTC]] (starting with [[Windows Vista#Service Pack 2|Vista SP2]]).<ref>{{cite web |first=Mike |last=Nash |url=http://windowsteamblog.com/blogs/windowsvista/archive/2008/10/24/windows-vista-service-pack-2-beta.aspx |archive-url=https://web.archive.org/web/20130509023652/http://blogs.windows.com/windows/archive/b/windowsvista/archive/2008/10/24/windows-vista-service-pack-2-beta.aspx |archive-date=May 9, 2013 |title=Windows Vista Service Pack 2 Beta |publisher=The Windows Blog |date=October 24, 2008 |url-status=dead }}</ref>
* Optional support for [[access-control list]]s (not currently supported in Windows Desktop/Server versions).<ref>{{cite web | url=http://www.anandtech.com/systems/showdoc.aspx?i=3233&p=4 | title=A Second Shot: Windows Vista SP1 | access-date=November 5, 2013 | archive-date=December 2, 2008 | archive-url=https://web.archive.org/web/20081202101342/http://www.anandtech.com/systems/showdoc.aspx?i=3233&p=4 | url-status=live }}</ref>
* Optional support for [[TexFAT]], a transactional file system standard (optionally [[WinCE]] activated function, not supported in Windows Desktop/Server versions).
* Boundary alignment offset for the FAT table.
* Boundary alignment offset for the data region.
* Provision for OEM-definable parameters to customize the file system for specific device characteristics.<ref name="microsoft.com" /><ref>{{cite web | url=http://msdn.microsoft.com/en-us/library/ee490605%28v=winembedded.60%29.aspx | title=OEM Parameter Definition with exFAT (Windows Embedded CE 6.0) | access-date=November 25, 2013 | archive-date=December 3, 2013 | archive-url=https://web.archive.org/web/20131203021913/http://msdn.microsoft.com/en-us/library/ee490605%28v=winembedded.60%29.aspx | url-status=live }}</ref>
* Valid data length (VDL): through the use of two distinct lengths fields{{snd}} one for "allocated space" and the other for "valid data"{{snd}} exFAT can preallocate a file without leaking data that was previously on-disk.
* [[Cluster (file system)|Cluster]] size up to 32&nbsp;MB.<ref name="Microsoft" />
* Metadata integrity with checksums.{{clarify|date=June 2014}}
* Template-based metadata structures.{{clarify|date=June 2014}}
* Removal of the physical {{code|.}} and {{code|..}} directory entries that appear in subdirectories.
* exFAT no longer stores the short [[8.3 filename]] references in directory structure and natively uses extended file names, whereas legacy FAT versions implement extended file names through the [[VFAT]] extension.

[[Windows XP]] requires update KB955704 to be installed, and [[Windows Vista]] requires its SP1 installed.<ref name="Microsoft"/><ref>{{Cite web|url=http://www.microsoft.com/en-us/legal/intellectualproperty/IPLicensing/Programs/exFATFileSystem.aspx|archive-url=https://web.archive.org/web/20130507183540/http://www.microsoft.com/en-us/legal/intellectualproperty/IPLicensing/Programs/exFATFileSystem.aspx|url-status=dead|title=Information about support for exFAT under Windows Vista.|website=[[Microsoft]]|archive-date=May 7, 2013}}</ref><ref>{{cite web|url=http://www.microsoft.com/en-us/download/details.aspx?id=30|title=Download Windows Vista Service Pack 1 Five Language Standalone (KB936330) from Official Microsoft Download Center|publisher=Microsoft|access-date=February 26, 2015|archive-date=February 26, 2015|archive-url=https://web.archive.org/web/20150226105901/http://www.microsoft.com/en-us/download/details.aspx?id=30|url-status=live}}</ref> Windows Vista is unable to use exFAT drives for [[ReadyBoost]]. [[Windows&nbsp;7]] removes this limitation, enabling ReadyBoost caches larger than 4&nbsp;GB.<ref>{{cite web|url=http://www.tech-recipes.com/rx/2801/exfat_versus_fat32_versus_ntfs|title=exFAT Versus FAT32 Versus NTFS|date=February 27, 2008|access-date=October 2, 2009|archive-date=January 29, 2013|archive-url=https://web.archive.org/web/20130129045108/http://www.tech-recipes.com/rx/2801/exfat_versus_fat32_versus_ntfs/|url-status=live}}</ref> Windows&nbsp;10 only allows formatting exFAT and NTFS on non-removeable volumes sized larger than 32&nbsp;GB with the default user interface, and FAT32 format is suggested for smaller volumes; command-line utilities don't accept quick format using FAT32 if volume is larger than 32 GB.

The standard exFAT implementation is not [[Journaling file system|journaled]] and only uses a single file allocation table and free-space map. FAT file systems instead used alternating tables, as this allowed recovery of the file system if the media was ejected during a write (which occurs frequently in practice with removable media). The optional [[TexFAT]] component adds support for additional backup tables and maps, but may not be supported.

The exFAT format allows individual files larger than 4&nbsp;GB, facilitating long continuous recording of HD video, which can exceed the 4&nbsp;GB limit in less than an hour. Digital cameras using FAT32 will break the video files into multiple segments of approximately 2 or 4&nbsp;GB. 

EFS supported in Windows 10 v1607 and Windows Server 2016 or later.<ref>{{Cite web |title=[MS-FSCC]: Appendix B: Product Behavior |url=https://msdn.microsoft.com/en-us/library/cc232128.aspx#Appendix_A_140 |access-date=2017-10-02 |website=msdn.microsoft.com |language=en-us}}</ref> 

=== Efficiency ===
SDXC cards running at [[UHS-I]] have a minimum guaranteed write speed of 10&nbsp;MB/s, and exFAT plays a factor in achieving this throughput through the reduction of the file-system overhead in cluster allocation. This is achieved through the introduction of a separate cluster bitmap where the reservation state of each cluster (reserved/free) is tracked by only one bit, reducing writes to the much larger FAT that originally served this purpose. 

Additionally, a single bit in the directory record indicates that the file is contiguous (unfragmented), telling the exFAT driver to ignore the FAT. This optimization is analogous to an [[Extent (file systems)|extent]] in other file systems, except that it only applies to whole files, as opposed to contiguous parts of files.

== Adoption ==
exFAT is supported in [[Windows XP]] and [[Windows Server 2003]] with update KB955704,<ref name="xpkb" /> [[Windows Vista#Service Pack 1|Windows Vista Service Pack 1]] and later,<ref>{{cite web|url=http://windowsvistablog.com/blogs/windowsvista/pages/windows-vista-service-pack-1-beta-whitepaper.aspx#_Toc175944550|title=Vista SP1 Whitepaper|date=August 28, 2007|access-date=August 28, 2007|first=Brandon|last=LeBlanc|publisher=[[Microsoft]]|archive-date=September 2, 2007|archive-url=https://web.archive.org/web/20070902075248/http://windowsvistablog.com/blogs/windowsvista/pages/windows-vista-service-pack-1-beta-whitepaper.aspx#_Toc175944550|url-status=dead}}</ref> [[Windows Server 2008]] and later (except [[Server Core]]),<ref name="Server2008exFATsupport" /> [[macOS]] starting from 10.6.5, [[Linux]] via [[Filesystem in Userspace|FUSE]] or natively starting from kernel 5.4, and [[iPadOS]] as well as iOS starting from 13.1.<ref name="Mac OS X 10.6.5 Notes" /><ref name="fsck_exfat man"/><ref>{{Cite web |url=https://appleinsider.com/articles/19/06/07/how-to-use-external-storage-on-ipad-and-iphone-with-ios-13 |title=How to use external storage on iPad and iPhone with iOS 13 |first=Andrew |last=O'Hara |date=June 7, 2019 |website=AppleInsider |language=en |access-date=2020-02-26 |archive-date=2019-08-02 |archive-url=https://web.archive.org/web/20190802142532/https://appleinsider.com/articles/19/06/07/how-to-use-external-storage-on-ipad-and-iphone-with-ios-13 |url-status=live}}</ref>

Companies can integrate exFAT into a specific group of consumer devices, including cameras, camcorders, and digital photo frames for a [[flat fee]]. Mobile phones, PCs, and networks have a different volume pricing model.<ref name="flash-format" />

exFAT is supported in a number of media devices such as modern flat-panel TVs,<ref>{{cite web |url=http://esupport.sony.com/US/perl/support-info.pl?info_id=799&mdl=KDL46EX720 |title=exFAT support on Sony |access-date=January 6, 2013 |archive-date=February 19, 2012 |archive-url=https://web.archive.org/web/20120219004729/http://esupport.sony.com/US/perl/support-info.pl?info_id=799&mdl=KDL46EX720 |url-status=live }}</ref> media centers, and portable media players.<ref>{{cite web|url=http://paradigmsolutions.files.wordpress.com/2009/12/exfat-excerpt-1-4.pdf|first=Jeff|last=Hamm|publisher=[[CACI|Paradigm Solutions]]<!-- CACI acquired Paradigm Holdings in 2011. -->|year=2009|title=Extended FAT File System|access-date=April 9, 2013|archive-date=March 14, 2016|archive-url=https://web.archive.org/web/20160314105027/https://paradigmsolutions.files.wordpress.com/2009/12/exfat-excerpt-1-4.pdf|url-status=live}}</ref>

exFAT is the official file system of [[SDXC]] cards. Because of this, any device not supporting exFAT, such as the [[Nintendo 3DS]], may not legally advertise itself as SDXC compatible, despite supporting SDXC cards as mass storage devices by formatting the card with FAT32 or a proprietary file system tied to the device in question.

Some vendors of other flash media, including USB pen drives, compact flash (CF) and solid-state drives (SSD) ship some of their high-capacity media pre-formatted with the exFAT file system to ensure compatibility with any given device. For example, Sandisk ships their 256&nbsp;GB CF cards as exFAT.

Microsoft has entered into licensing agreements with [[BlackBerry Limited|BlackBerry]],<ref>{{Cite web|url=https://www.tomshardware.com/news/microsoft-file-system-smartphone,17723.html|title=Microsoft Licenses exFAT to Research In Motion|date=September 20, 2012|website=Tom's Hardware}}</ref><ref>{{cite press release |url=http://www.microsoft.com/en-us/news/Press/2012/Sep12/09-18RIMPR.aspx |title=Microsoft Signs Licensing Agreement With Research In Motion |date=18 September 2012 |publisher=Microsoft |access-date=17 March 2015 |archive-date=10 September 2014 |archive-url=https://web.archive.org/web/20140910034927/http://www.microsoft.com/en-us/news/press/2012/sep12/09-18rimpr.aspx |url-status=live }}</ref> [[Panasonic]], [[Sanyo]], [[Sony]], [[Canon Inc.|Canon]], [[Aspen Avionics]],<ref>{{cite press release |url=http://www.microsoft.com/en-us/news/Press/2012/May12/05-03AspenPR.aspx |title=Microsoft Signs Patent Licensing Agreement With Aspen Avionics |publisher=Microsoft |access-date=2013-05-13 |archive-date=2013-05-15 |archive-url=https://web.archive.org/web/20130515185505/http://www.microsoft.com/en-us/news/Press/2012/May12/05-03AspenPR.aspx |url-status=live }}</ref> [[Audiovox]], [[Continental AG|Continental]], [[Harman International Industries|Harman]], [[LG|LG Automotive]]<ref>{{Cite web|url=https://news.microsoft.com/2013/06/19/in-vehicle-infotainment-gets-boost-from-new-microsoft-exfat-file-system-deals-2/|title=In-vehicle infotainment gets boost from new Microsoft exFAT file system deals|date=June 19, 2013|website=Stories|access-date=July 28, 2019|archive-date=July 28, 2019|archive-url=https://web.archive.org/web/20190728221459/https://news.microsoft.com/2013/06/19/in-vehicle-infotainment-gets-boost-from-new-microsoft-exfat-file-system-deals-2/|url-status=live}}</ref> and [[BMW]].<ref>{{cite press release|url=http://www.microsoft.com/en-us/news/Press/2013/Jan13/01-16BMWPR.aspx|title=Microsoft Signs exFAT Licensing Agreement With BMW|publisher=Microsoft|access-date=2013-01-17|archive-date=2013-01-19|archive-url=https://web.archive.org/web/20130119035046/http://www.microsoft.com/en-us/news/Press/2013/Jan13/01-16BMWPR.aspx|url-status=live}}</ref>

[[Mac&nbsp;OS&nbsp;X Snow Leopard]] 10.6.5 and later can create, read, write, verify, and repair exFAT file systems.<ref name="Mac OS X 10.6.5 Notes"/><ref name="fsck_exfat man" />

Linux has support for exFAT via [[Filesystem in Userspace|FUSE]] since 2009.<ref name="exfat-fuse" /> In 2013, [[Samsung Electronics]] published a Linux [[device driver|driver]] for exFAT under [[GPL]].<ref>{{Cite web|url=https://sfconservancy.org/news/2013/aug/16/exfat-samsung/|title=Conservancy Helps Samsung Resolve GPL Compliance Matter Amicably|website=Software Freedom Conservancy|language=en|access-date=2019-03-15|archive-date=2019-02-03|archive-url=https://web.archive.org/web/20190203131826/https://sfconservancy.org/news/2013/aug/16/exfat-samsung/|url-status=live}}</ref>
On 28 August 2019, Microsoft published the exFAT specification<ref name="exfatspec" /> and released the patent to the [[Open Invention Network]] members.<ref name="exfatOIN">{{Cite web|title=exFAT in the Linux kernel? Yes!|url=https://cloudblogs.microsoft.com/opensource/2019/08/28/exfat-linux-kernel/|publisher=Microsoft|author=John Gossman|date=2019-08-28|access-date=2019-09-02|archive-date=2019-09-01|archive-url=https://web.archive.org/web/20190901180353/https://cloudblogs.microsoft.com/opensource/2019/08/28/exfat-linux-kernel/|url-status=live}}</ref> The [[Linux kernel]] introduced native exFAT support with the 5.4 release in November 2019.<ref name="Linux Kernel 5.4 Release Features"/>

[[ChromeOS]] can read and write to exFAT partitions.<ref name="chromeOS">{{Cite web |title=File types and external devices that work on Chromebooks |url=https://support.google.com/chromebook/answer/183093?hl=en#zippy=%2Cfilesystems |publisher=Google Inc. |author=<!--Not stated--> |access-date=2021-06-08 |archive-date=2014-01-11 |archive-url=https://web.archive.org/web/20140111120552/https://support.google.com/chromebook/answer/183093?hl=en#zippy=%2Cfilesystems |url-status=live}}</ref>

[[OpenHarmony]] operating system since 3.1 version in December 2021, alongside [[HarmonyOS]] platform with [[HarmonyOS NEXT]] Beta update add native support for read and write exFAT partitions.<ref>{{cite web |last1=Sarkar |first1=Amy |title=New HarmonyOS NEXT adds exFAT support and charging improvements |url=https://www.huaweicentral.com/harmonyos-next-beta-adds-exfat/ |website=HC Newsroom |date=13 October 2024 |access-date=13 October 2024}}</ref>

== Technical specifications ==

{| class="wikitable" style="float:right; margin:10px;"
|+ Default exFAT cluster sizes in Windows
|-
! Volume<br>size
! Cluster<br>size
! Cluster<br>count
|-
|{{0|00}}7 MB to <256 MB || {{0|00}}4 KB || <{{0|000}}65,536
|-
|256 MB to <{{0|0}}32 GB || {{0}}32 KB || <{{0|0}}1,048,576
|-
|{{0}}32 GB to <512 GB<ref group=upper-alpha name=32GB_exFAT_Windows10/><ref group=upper-alpha name=128KB_clusters/>|| 128 KB || rowspan="8" | <{{0|0}}4,194,304
|-
|512 GB to <{{0|00}}1 TB || 256 KB
|-
|{{0|00}}1 TB to <{{0|00}}2 TB || 512 KB
|-
|{{0|00}}2 TB to <{{0|00}}4 TB || {{0|00}}1 MB
|-
|{{0|00}}4 TB to <{{0|00}}8 TB || {{0|00}}2 MB
|-
|{{0|00}}8 TB to <{{0|0}}16 TB || {{0|00}}4 MB
|-
|{{0}}16 TB to <{{0|0}}32 TB || {{0|00}}8 MB
|-
|{{0}}32 TB to <{{0|0}}64 TB || {{0}}16 MB
|-
|{{0}}64 TB to <512 TB || {{0}}32 MB || <16,777,216
|-
|colspan="3" style="width:256px;" |Notes: {{reflist|group=upper-alpha|refs=
<ref name=32GB_exFAT_Windows10> Windows 8/10 defaults to exFAT on volumes sized ≥32 GB, and FAT32 on volumes <32 GB.</ref> 
<ref name=128KB_clusters>Windows XP/Vista/7 defaults to 128 KB clusters for volumes sized ≥32 GB.</ref> 
}}
|} 

=== File name lookup ===
exFAT employs a filename hash-based lookup phase to speed certain cases, which is described in US patent ''Quick File Name Lookup Using Name Hash''.<ref name="uspatent">{{Cite patent |country=US |number=8321439 |pubdate=2012-11-27 |title=Quick filename lookup using name hash |assign1=[[Microsoft Corp.]] |inventor1-last=Pudipeddi |inventor1-first=Ravisankar V. |inventor2-last=Ghotge |inventor2-first=Vishal V. |inventor3-last=Thind |inventor3-first=Ravinder S.}}; contains Microsoft exFAT specification (revision 1.00).</ref> Appendix&nbsp;A of the document contains details helpful in understanding the file system.

=== File and cluster pre-allocation ===
Like NTFS, exFAT can pre-allocate disk space for a file by just marking arbitrary space on disk as "allocated". For each file, exFAT uses two separate 64-bit fields in the directory: the valid data length (VDL), which indicates the real size of the file, and the physical data length.

To provide improvement in the allocation of cluster storage for a new file, Microsoft incorporated a method to pre-allocate contiguous clusters and bypass the use of updating the FAT table, which was patented December&nbsp;10, 2013.<ref>{{Cite patent |country=US |number=8606830 |pubdate=2013-12-10 |title=Contiguous file allocation in an extensible file system |assign1=[[Microsoft Corp.]] |inventor1-last=Pudipeddi |inventor1-first=Ravisankar V. |inventor2-last=Ghotge |inventor2-first=Vishal V. |inventor3-last=Thind |inventor3-first=Ravinder S. |inventor4-last=Goebel |inventor4-first=David A.}}</ref> One feature of exFAT (used in the exFAT implementation within embedded systems) provides atomic transactions for the multiple steps of updating the file-system metadata. The feature called ''Transaction Safe FAT'', or [[TexFAT]], was granted a patent on November&nbsp;3, 2009.<ref>{{Cite patent |country=US |number=7613738 |pubdate=2009-11-03 |title=FAT directory structure for use in transaction safe file system |assign1=[[Microsoft Corp.]] |inventor1-last=Patel |inventor1-first=Sachin |inventor2-last=Gopalan |inventor2-first=Yadhu |inventor3-last=Rogers |inventor3-first=Andrew}}</ref>

=== Directory file set ===
exFAT and the rest of the FAT family of file systems do not use indexes for file names, unlike NTFS, which uses [[B-trees]] for file searching. When a file is accessed, the directory must be sequentially searched until a match is found. For file names shorter than 16&nbsp;characters in length, one file name record is required but the entire file is represented by three 32-byte directory records. This is called a directory file set, and a 256&nbsp;MB sub-directory can hold up to 2,796,202 file sets. (If files have longer names, this number will decrease, but this is the maximum based on the minimal three-record file set.) To help improve the sequential searching of the directories (including the root) a hash value of the file name is derived for each file and stored in the directory record. When searching for a file, the file name is first converted to upper case using the upcase table (file names are case-insensitive) and then hashed using a proprietary patented algorithm into a 16-bit (2-byte) hash value. Each record in the directory is searched by comparing the hash value. When a match is found, the file names are compared to ensure that the proper file was located in case of hash collisions. This improves performance because only 2&nbsp;bytes have to be compared for each file. This significantly reduces the CPU load because most file names are more than 2&nbsp;characters (bytes) in size and virtually every comparison is performed on only 2&nbsp;bytes at a time until the intended file is located.

=== Metadata and checksums ===
exFAT introduces metadata integrity through the use of checksums. There are three checksums currently in use.
# The [[volume boot record]] (VBR) is a 12-sector region that contains the boot records, [[BIOS parameter block]] (BPB), OEM parameters and the checksum sector. (There are two VBR type regions, the main VBR and the backup VBR.) The checksum sector is a checksum of the previous 11 sectors, with the exception of three bytes in the boot sector (flags and percent used). This provides integrity of the VBR by determining whether the VBR was modified. The most common cause could be a [[Boot sector#Boot-sector viruses|boot-sector virus]], but this would also catch any other corruption to the VBR.
# A second checksum is used for the upcase table. This is a static table and should never change. Any corruption in the table could prevent files from being located because this table is used to convert the filenames to upper case when searching to locate a file.
# The third checksum is in the directory file sets. Multiple directory records are used to define a single file, and this is called a file set. This file set has metadata including the file name, time stamps, attributes, address of first cluster location of the data, file lengths, and the file name. A checksum is taken over the entire file set, and a mismatch would occur if the directory file set was accidentally or maliciously changed.

When the file system is mounted, and the integrity check is conducted, these hashes are verified. Mounting also includes comparison of the version of the exFAT file system by the driver to make sure the driver is compatible with the file system it is trying to mount, and to make sure that none of the required directory records are missing (for example, the directory record for the upcase table and allocation bitmap are required, and the file system can't run if they are missing). If any of these checks fail, the file system should not be mounted, although in certain cases it may mount read-only.

The file system provides extensibility through template-based metadata definitions using generic layouts and generic patterns.<ref>{{Cite patent|country=US|number=10614032|pubdate=2020-04-07|title=Quick filename lookup using name hash|assign1=[[Microsoft Corp.|Microsoft Technology Licensing LLC]]|inventor1-last=Pudipeddi|inventor1-first=Ravisankar V.|inventor2-last=Ghotge|inventor2-first=Vishal V.|inventor3-last=Thind|inventor3-first=Ravinder S.}}; contains exFAT specification revision 1.00. See Tables 8, 12, 13, 14, 15, 16, 17.</ref><ref>{{Cite patent|country=US|number=9639554|pubdate=2017-05-02|title=Extensible file system|assign1=[[Microsoft Corp.|Microsoft Technology Licensing LLC]]|inventor1-last=Pudipeddi|inventor1-first=Ravisankar V.|inventor2-last=Ghotge|inventor2-first=Vishal V.|inventor3-last=Havewala|inventor3-first=Sarosh C.|inventor4=Ravinder S. Thind;Mark J. Zbikowski}}; states in abstract and elsewhere that directory records can be custom-defined.</ref>

=== Flash optimizations ===
exFAT contains features that, according to Microsoft, make it flash-friendly:
* Boundary alignment for filesystem structures. The offsets for the FAT and the cluster heap is adjustable at format time, so that writes to these areas will happen in as few flash blocks as possible.
* An "OEM parameters" field can be used to record features such as block size of the underlying storage. One single type for flash storage is pre-defined.<ref name=CE-flash>{{cite web |title=OEM Parameter Definition with exFAT (Windows Embedded CE 6.0) |url=https://docs.microsoft.com/en-us/previous-versions/windows/embedded/ee490605(v=winembedded.60) |website=Microsoft documentation | date=5 January 2012 |language=en-us |access-date=2020-04-17 |archive-date=2020-07-26 |archive-url=https://web.archive.org/web/20200726013841/https://docs.microsoft.com/en-us/previous-versions/windows/embedded/ee490605(v=winembedded.60) |url-status=live }}</ref>
* The lack of a [[Journaling file system|journal]], so that less data is written. (Although FAT32 also lacks a journal.)

The first feature requires support from the formatting software. Compliant implementations will follow existing offsets. The OEM parameter may be ignored. Implementations may also use [[Trim (computing)|TRIM]] to reduce wear.

{|class=wikitable
|+ Flash device features in exFAT implementations
!
! Boundary alignment (format)
! OEM parameters (use)
! TRIM (use)
! Note
|-
!scope=row| Windows CE
| {{yes}} || {{yes}} || {{unknown}}
|
|-
!scope=row| Windows Desktop and Server
| {{yes}} || {{yes}} || {{no}}
|
|-
!scope=row| Linux kernel
| {{Yes|since 5.7}}<ref name=phoronix_april_04_2020>{{cite web | last1=Larabel | first1=Michael | url=https://www.phoronix.com/scan.php?page=news_item&px=Linux-5.7-New-exFAT-Lands | title=The New Microsoft exFAT File-System Driver Has Landed In Linux 5.7 | website=Phoronix | access-date=March 11, 2021 | date=April 4, 2020 | archive-date=March 5, 2021 | archive-url=https://web.archive.org/web/20210305195345/https://www.phoronix.com/scan.php?page=news_item&px=Linux-5.7-New-exFAT-Lands | url-status=live }}</ref> || {{no|ignored}} || {{yes|since 5.13}}<ref>{{Cite web|url=https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit?id=654762df2ec7d61b05acc788afbffaba52d658fe|title=Kernel/Git/Torvalds/Linux.git - Linux kernel source tree|access-date=2021-10-14|archive-date=2021-04-30|archive-url=https://web.archive.org/web/20210430080309/https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=654762df2ec7d61b05acc788afbffaba52d658fe|url-status=live}}</ref>
| exfatprogs<ref>{{man|8|mkfs.exfat|Linux}}</ref> is assumed to be used for formatting.
|}

== Other implementations ==
=== Legal status ===
exFAT was a proprietary file system until 2019, when Microsoft released the specification and allowed [[Open Invention Network]] (OIN) members to use their patents.<ref>{{cite web |last1=Larabel |first1=Michael |title=Microsoft Publishes exFAT Specification, Encourages Linux Support |url=https://www.phoronix.com/scan.php?page=news_item&px=Microsoft-exFAT-Specification |website=Phoronix |access-date=28 August 2019 |date=28 August 2019 |archive-date=3 September 2019 |archive-url=https://web.archive.org/web/20190903055041/https://www.phoronix.com/scan.php?page=news_item&px=Microsoft-exFAT-Specification |url-status=live }}</ref> This lack of documentation along with the threat of a patent infringement lawsuit, as happened previously when Microsoft sued various companies over the VFAT long file name patent (before it expired), hampered the development of [[free and open-source]] drivers for exFAT, and led to a situation where Linux distributions could not even tell users how to get an exFAT driver. Accordingly, exFAT official support was effectively limited to Microsoft's own products and those of Microsoft's licensees. This, in turn, inhibited exFAT's adoption as a universal exchange format, as it was safer and easier for vendors to rely on FAT32 than it was to pay Microsoft or risk being sued.

[[Interoperability]] requires that certain results be achieved in a particular, predefined way (an [[algorithm]]). For exFAT, this potentially requires every implementation to perform certain procedures in exactly the same way as Microsoft's implementation. Some of the procedures used by Microsoft's implementation are patented, and these patents are owned by Microsoft.<ref name="exfat-licensing" /> A license to use these algorithms can be purchased from Microsoft,<ref>{{citation |last=Protalinski |first=Emil |title=Microsoft licenses out exFAT file system |journal=ArsTechnica |date=December 10, 2009 |url=https://arstechnica.com/information-technology/2009/12/microsoft-licenses-out-exfat-file-system/ |access-date=November 18, 2017 |archive-date=July 8, 2017 |archive-url=https://web.archive.org/web/20170708115438/https://arstechnica.com/information-technology/2009/12/microsoft-licenses-out-exfat-file-system/ |url-status=live}}.</ref><ref name="exfat-licensing" /> and some companies{{snd}} including [[Apple Inc.|Apple]], [[Google]] and [[Samsung]]{{snd}} have done so.<ref name="Girard" /> However, in the [[Business models for open-source software|open-source ecosystem]], users have typically responded to vendors being unwilling to pay for patent licenses by procuring an implementation for themselves from unofficial sources. For example, this is what happened with [[LAME]] when [[MP3]] patents were still valid. (Alternatively, the user may decide that the feature is unimportant to them.)

Regardless of whether open-source or not, Microsoft stated that "a license is required in order to implement exFAT and use it in a product or device".<ref name="exfat-licensing" /> Unlicensed distribution of an exFAT driver would make the distributor liable for financial damages if the driver is found to have violated Microsoft's patents.<ref>{{citation|last=Corbet|first=Jonathan|date=July 24, 2013|title=The exfiltrated exFAT driver|series=LWN|url=https://lwn.net/Articles/560424/|access-date=November 25, 2013|archive-date=December 2, 2013|archive-url=https://web.archive.org/web/20131202222012/https://lwn.net/Articles/560424/|url-status=live}}.</ref><ref>{{citation|last1=Finley|first1=Klint|last2=McMillan|first2=Robert|date=July 25, 2013|title=Free Software Robin Hood Liberates Leaked Samsung Code|journal=Wired Magazine|url=https://www.wired.com/2013/07/samsung-code/|access-date=November 18, 2017|archive-date=June 28, 2018|archive-url=https://web.archive.org/web/20180628080450/https://www.wired.com/2013/07/samsung-code/|url-status=live}}.</ref> While the patents may not be enforceable, this can only be determined through a legal process, which is expensive and time-consuming. It may also be possible to achieve the intended results without infringing Microsoft's patents.<ref>{{citation|last=Else|first=Sylvia|title=exFat patent avoidance|series=Linux.com kernel development forums|date=November 19, 2016|url=https://www.linux.com/forums/kernel-development/exfat-patent-avoidance|access-date=November 18, 2017|archive-date=December 1, 2017|archive-url=https://web.archive.org/web/20171201030451/https://www.linux.com/forums/kernel-development/exfat-patent-avoidance|url-status=live}}.</ref> In October 2018, Microsoft released 60,000 patents to the OIN members for Linux systems, but exFAT patents were not initially included at the time. There was, however, discussion within Microsoft over whether Microsoft should allow exFAT in Linux devices,<ref>{{Cite web|url=https://www.zdnet.com/article/what-does-microsoft-joining-the-open-invention-network-mean-for-you/|title=What does Microsoft joining the Open Invention Network mean for you?|last=Vaughan-Nichols|first=Steven J.|website=ZDNet|access-date=2018-12-29|archive-date=2019-02-07|archive-url=https://web.archive.org/web/20190207075332/https://www.zdnet.com/article/what-does-microsoft-joining-the-open-invention-network-mean-for-you/|url-status=live}}</ref><ref>{{Cite web|last1=Larabel|first1=Michael|url=https://www.phoronix.com/scan.php?page=news_item&px=Linux-exFAT-2019-Discussion|title=Merging exFAT Support For Linux Is Being Talked About - Waiting On Microsoft's Blessing - Phoronix|website=www.phoronix.com|access-date=2019-08-08|date=July 10, 2019|archive-date=2019-08-08|archive-url=https://web.archive.org/web/20190808191418/https://www.phoronix.com/scan.php?page=news_item&px=Linux-exFAT-2019-Discussion|url-status=live}}</ref> which eventually resulted in Microsoft publishing the official specification for open usage<ref name="exfatspec" /> and releasing the exFAT patents to the OIN in August 2019.<ref name="exfatOIN" />

=== List of implementations ===
A [[Filesystem in Userspace|FUSE]]-based implementation named fuse-exfat, or exfat-fuse,<ref name="exfat-fuse" /> with read/write support is available for [[FreeBSD]], multiple [[Linux]] distributions, and older versions of [[Mac OS X]]. It supports TRIM.<ref>{{cite web |url=https://groups.google.com/group/fa.linux.kernel/browse_thread/thread/903eb182127e8f21/e2e23eeb3a016268 |title=exFAT fs and Linux |access-date=September 28, 2009 |archive-date=September 16, 2009 |archive-url=https://web.archive.org/web/20090916012023/http://groups.google.com/group/fa.linux.kernel/browse_thread/thread/903eb182127e8f21/e2e23eeb3a016268 |url-status=live }}{{unreliable source?|date=November 2013}}</ref><ref>{{cite web |url=https://github.com/relan/exfat |title=exFAT fs on FUSE |website=[[GitHub]] |access-date=May 15, 2010 |archive-date=December 31, 2015 |archive-url=https://web.archive.org/web/20151231012905/https://github.com/relan/exfat |url-status=live }}</ref><ref>{{cite web |url=http://apcmag.com/how-to-enable-exfat-in-ubuntu.htm |title=exFAT fs on linux UBUNTU |access-date=October 11, 2012 |archive-date=September 28, 2012 |archive-url=https://web.archive.org/web/20120928003426/http://apcmag.com/how-to-enable-exfat-in-ubuntu.htm |url-status=live }}</ref><ref>{{cite web |url=http://www.freshports.org/sysutils/fusefs-exfat/ |title=exFAT in FreeBSD |access-date=April 8, 2013 |archive-date=June 15, 2013 |archive-url=https://web.archive.org/web/20130615065500/http://www.freshports.org/sysutils/fusefs-exfat/ |url-status=live }}</ref><ref>{{cite web |url=https://github.com/daniel-toman/homebrew-exfat |title=ExFAT support for Mac OS X 10.5 Leopard and 10.4 Tiger (via Homebrew and Fuse for macOS) |website=[[GitHub]] |access-date=July 6, 2018 |archive-date=October 13, 2019 |archive-url=https://web.archive.org/web/20191013061432/https://github.com/daniel-toman/homebrew-exfat |url-status=live }}</ref> An implementation called exFATFileSystem, based on fuse-exfat, is available for [[AmigaOS|AmigaOS 4.1]].<ref>{{cite web | url=http://amigaworld.net/modules/news/article.php?storyid=7321 | title=Amigaworld.net | access-date=February 18, 2015 | archive-date=February 26, 2015 | archive-url=https://web.archive.org/web/20150226093057/http://amigaworld.net/modules/news/article.php?storyid=7321 | url-status=live }}</ref>

A Linux kernel implementation by [[Samsung Electronics]] is available.<ref>{{cite web | url=http://opensource.samsung.com/reception/receptionSub.do?method=sub&sub=F&searchValue=exfat | title=Open Source Release Center | publisher=Samsung | access-date=November 25, 2013 | archive-date=December 2, 2013 | archive-url=https://web.archive.org/web/20131202224439/http://opensource.samsung.com/reception/receptionSub.do?method=sub&sub=F&searchValue=exfat | url-status=live }}</ref> It was initially released on [[GitHub]] unintentionally,<ref>{{cite web | url=https://lwn.net/Articles/560424/ | title=The exfiltrated exFAT driver | publisher=LWN.net | date=July 24, 2013 | access-date=November 25, 2013 | author=Corbet, Jonathan | author-link=Jonathan Corbet | archive-date=December 2, 2013 | archive-url=https://web.archive.org/web/20131202222012/https://lwn.net/Articles/560424/ | url-status=live }}</ref> and later released officially by Samsung in compliance with the [[GPL]]v2 in 2013.<ref>{{cite web | url=http://sfconservancy.org/news/2013/aug/16/exfat-samsung/ | title=Conservancy Helps Samsung Resolve GPL Compliance Matter Amicably | publisher=Software Freedom Conservancy | date=August 16, 2013 | access-date=November 25, 2013 | archive-date=November 20, 2013 | archive-url=https://web.archive.org/web/20131120031442/http://sfconservancy.org/news/2013/aug/16/exfat-samsung/ | url-status=live }}</ref><ref name=bkuhn-exfat /> (This release does not make exFAT royalty-free, as licensing from Samsung does not remove Microsoft's patent rights.)<ref>{{citation|last=Corbet|first=Jonathan|date=August 16, 2013|title=Samsung releases exFAT filesystem source|series=LWN|url=https://lwn.net/Articles/563687/|access-date=November 18, 2017|archive-date=July 31, 2017|archive-url=https://web.archive.org/web/20170731151644/https://lwn.net/Articles/563687/|url-status=live}}.</ref><ref>{{citation|last=McMillan|first=Robert|date=August 20, 2013|title=Busted for Dodging Linux License, Samsung Makes Nice With Free Code|website=Wired.com|url=https://www.wired.com/2013/08/samsung-exfat/|access-date=November 18, 2017|archive-date=September 6, 2020|archive-url=https://web.archive.org/web/20200906183847/https://www.wired.com/2013/08/samsung-exfat/|url-status=live}}.</ref> A version of this driver was first incorporated into version 5.4 of the Linux kernel.<ref name=phoronix_sep_29_2019>{{cite web | last1=Larabel | first1=Michael | url=https://www.phoronix.com/scan.php?page=article&item=linux-54-features&num=1 | title=Linux 5.4 Features Are Huge From exFAT To New GPUs To Enabling Lots Of New Hardware | website=Phoronix | access-date=March 11, 2021 | date=September 29, 2019 | archive-date=April 10, 2021 | archive-url=https://web.archive.org/web/20210410144342/https://www.phoronix.com/scan.php?page=article&item=linux-54-features&num=1 | url-status=live }}</ref><ref name=phoronix_nov_17_2019>{{cite web | last1=Larabel | first1=Michael | url=https://www.phoronix.com/scan.php?page=news_item&px=Linux-5.4-Feature-Reminder | title=The Exciting Linux 5.4 Changes From exFAT Support To Intel Tiger Lake Graphics | website=Phoronix | access-date=March 11, 2021 | date=November 17, 2019 | archive-date=March 4, 2021 | archive-url=https://web.archive.org/web/20210304064244/https://www.phoronix.com/scan.php?page=news_item&px=Linux-5.4-Feature-Reminder | url-status=live }}</ref><ref name=phoronix_nov_24_2019>{{cite web | last1=Larabel | first1=Michael | url=https://www.phoronix.com/scan.php?page=news_item&px=Linux-5.4-Released | title=Linux 5.4 Kernel Released With exFAT Support, Faster Radeon Graphics, New Hardware | website=Phoronix | access-date=March 11, 2021 | date=November 24, 2019 | archive-date=March 9, 2021 | archive-url=https://web.archive.org/web/20210309020513/https://www.phoronix.com/scan.php?page=news_item&px=Linux-5.4-Released | url-status=live }}</ref> A much newer version of the driver, with several bug fixes and improved reliability, was incorporated into kernel 5.7.<ref name=phoronix_jan_20_2020>{{cite web | last1=Larabel | first1=Michael | url=https://www.phoronix.com/scan.php?page=news_item&px=Samsung-Better-exFAT-v11 | title=Samsung's Better exFAT Driver Gets Revised Ahead Of Mainline Linux Integration | website=Phoronix | access-date=March 11, 2021 | date=January 20, 2020 | archive-date=May 16, 2021 | archive-url=https://web.archive.org/web/20210516191439/https://www.phoronix.com/scan.php?page=news_item&px=Samsung-Better-exFAT-v11 | url-status=live }}</ref><ref name=phoronix_april_04_2020></ref> Prior to its being merged into the Linux kernel, this newer version had already seen adoption on Android smartphones and continued to be used on both Linux and Android thereafter.<ref name=phoronix_dec_30_2019>{{cite web | last1=Larabel | first1=Michael | url=https://www.phoronix.com/scan.php?page=news_item&px=exFAT-Newer-Option-v8 | title=Linux's exFAT Driver Looking To Still Be Replaced By A Newer Driver From Samsung | website=Phoronix | access-date=March 11, 2021 | date=December 30, 2019 | archive-date=March 5, 2021 | archive-url=https://web.archive.org/web/20210305143208/https://www.phoronix.com/scan.php?page=news_item&px=exFAT-Newer-Option-v8 | url-status=live }}</ref><ref name=phoronix_march_07_2020>{{cite web | last1=Larabel | first1=Michael | url=https://www.phoronix.com/scan.php?page=news_item&px=New-exFAT-For-Linux-5.7 | title=The New Microsoft exFAT File-System Driver Is Set To Land With Linux 5.7 | website=Phoronix | access-date=March 11, 2021 | date=March 7, 2020 | archive-date=April 23, 2021 | archive-url=https://web.archive.org/web/20210423101648/https://www.phoronix.com/scan.php?page=news_item&px=New-exFAT-For-Linux-5.7 | url-status=live }}</ref>

Proprietary read/write solutions licensed and derived from the Microsoft exFAT implementation are available for [[Android (operating system)|Android]],<ref name="reg120808" /> Linux, and other operating systems from [[Paragon Software Group]] and [[Tuxera]].

XCFiles (from [[Datalight]]) is a proprietary, full-featured implementation, intended to be portable to 32-bit systems.<ref>{{cite web | url=http://www.datalight.com/products/filesystems/xcfiles | title=XCFiles | access-date=June 21, 2010 | archive-date=July 30, 2010 | archive-url=https://web.archive.org/web/20100730023249/http://www.datalight.com/products/filesystems/xcfiles | url-status=dead }}</ref> Rtfs (from EBS Embedded Software) is a full-featured implementation for embedded devices.<ref>{{cite web | url=http://www.ebsembeddedsoftware.com/NewWebSite/AboutRtfs.html | title=Rtfs | access-date=January 19, 2011 | archive-date=June 12, 2011 | archive-url=https://web.archive.org/web/20110612004409/http://www.ebsembeddedsoftware.com/NewWebSite/AboutRtfs.html | url-status=live }}</ref>

Two experimental, unofficial solutions are available for DOS. The loadable USBEXFAT driver requires Panasonic's USB stack for DOS and only works with USB storage devices; the open-source EXFAT executable is an exFAT file-system reader and requires the [[HX&nbsp;DOS]] extender to work.<ref>{{cite web |url=http://www.mdgx.com/secrets.htm#XFAT |title=exFAT |date=February 2, 2011}}</ref> There are no native exFAT real-mode DOS drivers, which would allow usage of, or booting from, exFAT volumes.

The renaming of exFAT file system labels is natively supported by Microsoft [[Windows Explorer]], while [[Linux]] relies on the <code>exfatlabel</code> and <code>tune.exfat</code> tools (both part of exfatprogs).<ref>{{man|8|exfatlabel|Linux}}<br>{{man|8|tune.exfat|Linux}}</ref>

== See also ==
* [[Design of the FAT file system]]
* [[List of file systems]]
* [[Comparison of file systems]]
* [[Memory Stick XC]]
* [[Universal Disk Format]]

== Notes ==
{{reflist|group="nb"|refs=

<ref group="nb" name="NB_Size_File">
Although Microsoft published a different value in KB955704, the file size is in bytes and is stored as a 64-bit number. The largest theoretical file size would be 16&nbsp;EB&nbsp;−&nbsp;1&nbsp;byte, the same as in NTFS. However, since the maximum volume size under the current specification cannot exceed ~128&nbsp;PB, a file can never reach that file length.
</ref>

<ref group="nb" name="NB_Size_Volume">The theoretical maximum volume size is defined by up to 2{{sup|32}}&nbsp;−&nbsp;11 possible clusters with up to 2{{sup|25}}&nbsp;bytes per cluster ≈ 128&nbsp;PB. The cluster count is limited to 32-bit integers. The cluster size is not limited by data type; it's probably set in consideration of the [[LBA48]] addressing scheme, as with a 512-byte sector size, only 2{{sup|48}} × 512 = 2{{sup|57}}&nbsp;bytes = 128&nbsp;PB can be addressed.</ref>

<ref group="nb" name="NB_Count_Files">This limit applies because the maximum directory size is 256&nbsp;MB.</ref>

<ref group="nb" name="NB_NUM-CLUST">268,304,373 files = 2{{sup|28}} − 11 reserved clusters − 131,072, the minimum number of 64&nbsp;KB clusters occupied for the 268,435,445 directory entries (32&nbsp;bytes) without VFAT LFNs, which are required for 268,435,445 files with sizes between 1 and 65,535&nbsp;bytes. With VFATs, the 131,072 number must be multiplied by 21 (worst case), which would result in 265,682,933 files instead.</ref>

}}

== References ==
{{reflist|30em|refs=
<ref name="exfat-fuse">{{cite web|url=https://github.com/relan/exfat|title=exfat -Free exFAT file system implementation|website=[[GitHub]]|access-date=October 14, 2015|archive-date=December 31, 2015|archive-url=https://web.archive.org/web/20151231012905/https://github.com/relan/exfat|url-status=live}}</ref>

<ref name="bkuhn-exfat">{{cite web |url=https://github.com/bkuhn/exfat |title=GPL'ed sources for the Samsung exfat module as released by Samsung |website=[[GitHub]] |access-date=2017-08-20}}</ref>

<ref name="exfat-licensing">{{citation|chapter=Licensing exFAT|title=Microsoft IP licensing|series=Microsoft Legal Resources|date=1 March 2017|chapter-url=https://www.microsoft.com/en-us/legal/intellectualproperty/mtl/exfat-licensing.aspx|access-date=1 March 2017|archive-date=2 March 2017|archive-url=https://web.archive.org/web/20170302032622/https://www.microsoft.com/en-us/legal/intellectualproperty/mtl/exfat-licensing.aspx|url-status=live}}</ref>

<ref name="Girard">{{citation|last=Girard|first=David|date=21 June 2013|title=Can Microsoft's exFAT file system bridge the gap between OSes?|journal=ArsTechnica|url=https://arstechnica.com/information-technology/2013/06/review-is-microsofts-new-data-sharing-system-a-cross-platform-savior/|access-date=18 November 2017|archive-date=1 December 2017|archive-url=https://web.archive.org/web/20171201034346/https://arstechnica.com/information-technology/2013/06/review-is-microsofts-new-data-sharing-system-a-cross-platform-savior/|url-status=live}}.</ref>

<ref name="microsoft.com">{{cite web|url=https://www.microsoft.com/en-us/legal/intellectualproperty/mtl/exfat-licensing.aspx|title=Licensing exFAT|website=[[Microsoft]]|access-date=March 1, 2017|archive-date=March 2, 2017|archive-url=https://web.archive.org/web/20170302032622/https://www.microsoft.com/en-us/legal/intellectualproperty/mtl/exfat-licensing.aspx|url-status=live}}</ref>

<ref name="Microsoft">{{cite web|url=http://support.microsoft.com/kb/955704|title=Description of the exFAT file system driver update package|publisher=Microsoft|access-date=February 26, 2015|archive-date=February 26, 2015|archive-url=https://web.archive.org/web/20150226100703/http://support.microsoft.com/kb/955704|url-status=live}}</ref>

<ref name="xpkb">{{cite web |url=http://support.microsoft.com/?kbid=955704 |title=KB955704 |date=January 27, 2009 |quote=Description of the exFAT file system driver update package [for Windows XP and Windows Server 2003] |access-date=January 27, 2009 |archive-date=May 24, 2011 |archive-url=https://web.archive.org/web/20110524074113/http://support.microsoft.com/?kbid=955704 |url-status=live }}</ref>

<ref name="Server2008exFATsupport">{{cite web|url = https://technet.microsoft.com/en-us/library/dd163551.aspx|title = Adding Hard Disk Drives|publisher = Microsoft TechNet| access-date = September 15, 2009}}</ref>

<ref name="Mac OS X 10.6.5 Notes">{{cite web | url=http://www.macrumors.com/2010/11/11/mac-os-x-10-6-5-notes-exfat-support-airprint-flash-player-vulnerability-fixes/ | title=Mac OS X 10.6.5 Notes: exFAT Support, AirPrint, Flash Player Vulnerability Fixes | date=11 November 2010 | access-date=November 25, 2013 | archive-date=June 18, 2013 | archive-url=https://web.archive.org/web/20130618035257/http://www.macrumors.com/2010/11/11/mac-os-x-10-6-5-notes-exfat-support-airprint-flash-player-vulnerability-fixes/ | url-status=live }}{{unreliable source?|date=November 2013}}</ref>

<ref name="flash-format">{{cite web|url=http://news.softpedia.com/news/Microsoft-Licenses-Windows-7-s-exFAT-Flash-File-Format-129512.shtml|title=Microsoft Licenses Windows 7's exFAT Flash File Format|author=Marius Oiaga|date=December 11, 2009|publisher=Softpedia.com|access-date=December 12, 2009|archive-date=December 14, 2009|archive-url=https://web.archive.org/web/20091214075453/http://news.softpedia.com/news/Microsoft-Licenses-Windows-7-s-exFAT-Flash-File-Format-129512.shtml|url-status=live}}</ref>

<ref name="reg120808">{{Cite news |url=https://www.theregister.co.uk/2012/08/08/microsoft_samsung_exfat/ |title=Sharp cuts exFAT deal with Microsoft for Android mobes |first=Gavin |last=Clarke |work=[[The Register]] |date=August 8, 2012 |access-date=August 12, 2012 |archive-date=August 11, 2012 |archive-url=https://web.archive.org/web/20120811064325/http://www.theregister.co.uk/2012/08/08/microsoft_samsung_exfat/ |url-status=live }}</ref>

<ref name="fsck_exfat man">{{cite web | url=https://developer.apple.com/library/mac/#documentation/Darwin/Reference/ManPages/man8/fsck_exfat.8.html | title=fsck_exfat(8) Mac OS X Manual Page | access-date=November 25, 2013 | archive-date=June 2, 2012 | archive-url=https://web.archive.org/web/20120602013413/https://developer.apple.com/library/mac/#documentation/Darwin/Reference/ManPages/man8/fsck_exfat.8.html | url-status=live }}</ref>

<ref name="Linux Kernel 5.4 Release Features">{{cite web | url=https://itsfoss.com/linux-kernel-5-4/ | title=Linux Kernel 5.4 Release Features | access-date=April 1, 2020 | author=Abhishek Prakash | date=November 25, 2019 | publisher=itsfoss.com | archive-date=December 8, 2019 | archive-url=https://web.archive.org/web/20191208205043/https://itsfoss.com/linux-kernel-5-4/ | url-status=live }}</ref>

}}

== External links ==
* [https://docs.microsoft.com/en-gb/windows/win32/fileio/exfat-specification exFAT specification]
* [https://docs.microsoft.com/en-gb/windows/win32/fileio/filesystem-functionality-comparison File System Functionality Comparison of exFAT, FAT32, NTFS, UDF]
* [http://msdn2.microsoft.com/en-us/library/aa914353.aspx exFAT overview in Windows Embedded CE]
* [http://msdn.microsoft.com/en-us/library/aa915463.aspx Transaction-Safe FAT File System (TexFAT) overview in Windows Mobile 6.5]
* [http://download.microsoft.com/download/5/b/9/5b97017b-e28a-4bae-ba48-174cf47d23cd/STO072_WH06.ppt Personal Storage : Opportunities and challenges for pocket-sized storage devices in the Windows world] ([[Microsoft PowerPoint|PowerPoint]] presentation at WinHEC 2006)
* [https://web.archive.org/web/20101221232444/http://www.microsoft.com/about/legal/en/us/IntellectualProperty/IPLicensing/Programs/exFATFileSystem.aspx exFAT File System Licensing]
* [http://www.sans.org/reading-room/whitepapers/forensics/reverse-engineering-microsoft-exfat-file-system-33274 Reverse Engineering the Microsoft exFAT File System], SANS Institute.
* {{Cite patent|country=US|number=2009164440|status=application}}, ''"Quick Filename Lookup Using Name Hash"''; Microsoft Corp; contains exFAT specification revision 1.00.
* {{Cite patent|country=US|number=2009164539|status=application}}, ''"Contiguous File Allocation In An Extensible File System"''; Microsoft Corp.
* [https://web.archive.org/web/20110120184126/http://www.sdcard.org/developers/tech/sdxc exFAT ships on all SDXC Cards], SD Card Association
* [https://events.static.linuxfound.org/images/stories/pdf/lceu11_munegowda_s.pdf The Extended FAT file system:Differentiating with FAT32 file system], Linux Conference, October 2011.
* [http://infinityonloop.com/ntfs-vs-exfat-vs-fat32/ Benefits of exFAT over FAT32]

{{File systems}}
{{Windows Components}}

{{DEFAULTSORT:exFAT}}
[[Category:2006 software]]
[[Category:Flash file systems]]
[[Category:Windows CE]]
[[Category:Windows disk file systems]]
[[Category:File systems supported by the Linux kernel]]
[[Category:Computer-related introductions in 2006]]
[[he:ExFAT]]