Gigabyte

v t e Multiple-byte units
Decimal Value Metric 1000 103 kB kilobyte 10002 106 MB megabyte 10003 109 GB gigabyte 10004 1012 TB terabyte 10005 1015 PB petabyte 10006 1018 EB exabyte 10007 1021 ZB zettabyte 10008 1024 YB yottabyte 10009 1027 RB ronnabyte 100010 1030 QB quettabyte	Binary Value IEC Memory 1024 210 KiB kibibyte KB kilobyte 10242 220 MiB mebibyte MB megabyte 10243 230 GiB gibibyte GB gigabyte 10244 240 TiB tebibyte TB terabyte 10245 250 PiB pebibyte – 10246 260 EiB exbibyte – 10247 270 ZiB zebibyte – 10248 280 YiB yobibyte – 10249 290 – – 102410 2100 – –
Orders of magnitude of data

The gigabyte (

(SI). Therefore, one gigabyte is one billion bytes. The unit symbol for the gigabyte is GB.

This definition is used in all contexts of science (especially

gibibyte

(1GiB) of storage capacity.

In response to litigation over whether the makers of electronic storage devices must conform to Microsoft Windows' use of a binary definition of "GB" instead of the metric/decimal definition, the United States District Court for the Northern District of California rejected that argument, ruling that "the U.S. Congress has deemed the decimal definition of gigabyte to be the 'preferred' one for the purposes of 'U.S. trade and commerce.'"^[2][3]

Definition

The term gigabyte has a standard definition of 1000³ bytes, as well as a discouraged

that needed to be expressed in a power of 2, but lacked a convenient name. As 1024 (2¹⁰) is approximately 1000 (10³), roughly corresponding to SI multiples, it was used for binary multiples as well.

In 1998 the

. Nevertheless, the term gigabyte continues to be widely used with the following two different meanings:

Base 10 (decimal)

• 1 GB = 1000000000 bytes (= 1000³ B = 10⁹ B)

Based on powers of 10, this definition uses the prefix giga- as defined in the

Base 2 (binary)

• 1 GiB = 1073741824 bytes (= 1024³ B = 2³⁰ B).

The binary definition uses powers of the base 2, as does the architectural principle of binary computers. This usage is widely promulgated by some

.

Consumer confusion

Since the first disk drive, the

report size using binary multipliers. This discrepancy causes confusion, as a disk with an advertised capacity of, for example, 400 GB (meaning 400000000000bytes, equal to 372 GiB) might be reported by the operating system as "372 GB".

For

The difference between units based on decimal and binary prefixes increases as a

is under 96% of a mebibyte, and a gigabyte is just over 93% of a gibibyte value. This means that a 300 GB (279 GiB) hard disk might be indicated variously as "300 GB", "279 GB" or "279 GiB", depending on the operating system. As storage sizes increase and larger units are used, these differences become more pronounced.

US lawsuits

A lawsuit decided in 2019 that arose from alleged breach of contract and other claims over the binary and decimal definitions used for "gigabyte" have ended in favor of the manufacturers, with courts holding that the legal definition of gigabyte or GB is 1 GB = 1,000,000,000 (10⁹) bytes (the decimal definition). Specifically, the courts held that "the U.S. Congress has deemed the decimal definition of gigabyte to be the 'preferred' one for the purposes of 'U.S. trade and commerce' .... The California Legislature has likewise adopted the decimal system for all 'transactions in this state'."[2]

Earlier lawsuits had ended in settlement with no court ruling on the question, such as a lawsuit against drive manufacturer Western Digital.^[12][13] Western Digital settled the challenge and added explicit disclaimers to products that the usable capacity may differ from the advertised capacity.^[12] Seagate was sued on similar grounds and also settled.^[12][14]

Other contexts

Because of their physical design, the capacity of modern computer random access memory devices, such as

Software allocates memory in varying degrees of granularity as needed to fulfill data structure requirements and binary multiples are usually not required. Other computer capacities and rates, like

, and are usually presented in decimal units. For example, the manufacturer of a "300 GB" hard drive is claiming a capacity of 300000000000bytes, not 300 × 1024³ (which would be 322122547200) bytes.

Examples of gigabyte-sized storage

• One hour of
  Mbit
  /s is approximately 1 GB.
• Seven minutes of HDTV video at 19.39 Mbit/s is approximately 1 GB.
• 114 minutes of uncompressed CD-quality audio at 1.4 Mbit/s is approximately 1 GB.
• A single layer
  DVD+R
  disc can hold about 4.7 GB.
• A dual-layered
  DVD+R
  disc can hold about 8.5 GB.
• A single layer Blu-ray can hold about 25 GB.
• The largest Nintendo Switch cartridge available on the market holds about 32 GB.
• A dual-layered Blu-ray can hold about 50 GB.
• A triple-layered Ultra HD Blu-ray can hold about 100 GB.

Unicode character

The "gigabyte" symbol is encoded by Unicode at code point U+3387 ㎇ SQUARE GB.^[16]

See also

• Orders of magnitude (data)
• Binary prefix

References

External links

• http://physics.nist.gov/cuu/Units/binary.html
• http://www.quinion.com/words/turnsofphrase/tp-kib1.htm Archived 12 June 2004 at the Wayback Machine
• https://www.nist.gov/public_affairs/techbeat/tb9903.htm Archived 20 August 2016 at the Wayback Machine