Giga-

Laptop-hard-drive-exposed

Laptop hard drive, with its platter exposed.

Giga- (Template:IPAc-en or Template:IPAc-en) is a unit prefix in the metric system denoting a factor of a short-scale billion or long-scale milliard (10⁹ or 1,000,000,000). It has the symbol G.

Giga- is derived from the Greek word (gígas), meaning "giant". The Oxford English Dictionary reports the earliest written use of giga in this sense to be in the Reports of the IUPAC 14th Conférence Internationale de Chimie in 1947: "The following prefixes to abbreviations for the names of units should be used: G giga 10⁹×." However, it was already used in 1932 by the German organization Verband deutscher Elektrotechniker.

When referring to information units in computing, such as gigabyte, giga may sometimes mean Template:Gaps (2³⁰); this causes ambiguity. Standards organizations discourage this and use giga- to refer to 10⁹ in this context too.Template:Primary source inline Gigabit is only rarely used with the binary interpretation of the prefix. The binary prefix gibi has been adopted for 2³⁰, while reserving giga exclusively for the metric definition.

Pronunciation

In English, the prefix giga can be pronounced Template:IPAc-en (a hard g as in giggle), or Template:IPAc-en (a soft g as in gigantic, which shares gigaTemplate:'s Ancient Greek root). A prominent example of this latter pronunciation is found in the pronunciation of gigawatts in the 1985 film Back to the Future.

According to the American writer Kevin Self, a German committee member of the International Electrotechnical Commission proposed giga as a prefix for 10⁹ in the 1920s, drawing on a verse (evidently "Anto-logie") by the German humorous poet Christian Morgenstern that appeared in the third (1908) edition of his (Gallows Songs). This suggests that a hard German was originally intended as the pronunciation. Self was unable to ascertain when the (soft g) pronunciation came into occasional use, but claimed that as of 1995 it had returned to (hard g).

In 1998, a poll by the phonetician John C. Wells found that 84% of Britons preferred the pronunciation of gigabyte starting with (as in gig), 9% with (as in jig), 6% with (guy), and 1% with (as in giant).

Common usage

• gigahertz—clock rate of a CPU, for instance, 3 GHz = Template:Gaps
• gigabit—bandwidth of a network link, for instance, 1 Gbit/s = Template:Gaps.
• gigabyte—for instance, for hard disk capacity, 120 GB = Template:Gaps;
• gigayear or gigaannum—one billion (10⁹) years, sometimes abbreviated Gyr, but the preferred usage is Ga or, for years ago, GA.

Binary prefix

The notation represents 1,000,000,000 bytes or, in deprecated usage, 1,073,741,824 (2³⁰) bytes. Per IEC 60027-2 A.2 and ISO/IEC 80000 standards, the correct notation of 2³⁰ is gibi (symbol Gi). One gibibyte () is 1,073,741,824 bytes or approximately . Despite international standards, the use of = 2³⁰ B is widespread. A laptop advertised as having has 8,589,934,592 bytes of memory: , or .

See also

• Binary prefix
• Gigabit Ethernet
• SI prefix
• List of commonly used taxonomic affixes
• RKM code

External links

• BIPM website

SI prefixes

Prefix		Base 10	Decimal	Adoption
Name	Symbol
quetta	Q	1030	Template:Gaps	2022
ronna	R	1027	Template:Gaps
yotta	Y	1024	Template:Gaps	1991
zetta	Z	1021	Template:Gaps
exa	E	1018	Template:Gaps	1975
peta	P	1015	Template:Gaps
tera	T	1012	Template:Gaps	1960
giga	G	109	Template:Gaps
mega	M	106	Template:Gaps	1873
kilo	k	103	Template:Gaps	1795
hecto	h	102	100
deca	da	101	10
—	—	100	1	—
deci	d	10−1	0.1	1795
centi	c	10−2	0.01
milli	m	10−3	0.001
micro	μ	10−6	Template:Gaps	1873
nano	n	10−9	Template:Gaps	1960
pico	p	10−12	Template:Gaps
femto	f	10−15	Template:Gaps	1964
atto	a	10−18	Template:Gaps
zepto	z	10−21	Template:Gaps	1991
yocto	y	10−24	Template:Gaps
ronto	r	10−27	Template:Gaps	2022
quecto	q	10−30	Template:Gaps
Notes