Multiples of bytes

The gigabyte (ə-/)[1] is a multiple of the unit byte for digital information. The prefix giga means 109 in the International System of Units (SI). Therefore, one gigabyte is 1000000000bytes. The unit symbol for the gigabyte is GB.

This definition is used in all contexts of science, engineering, business, and many areas of computing, including hard drive, solid state drive, and tape capacities, as well as data transmission speeds. However, the term is also used in some fields of computer science and information technology to denote 1073741824 (10243 or 230) bytes, particularly for sizes of RAM. The use of gigabyte may thus be ambiguous. Hard disk capacities as described and marketed by drive manufacturers using the standard metric definition of the gigabyte, but when a 400-GB drive's capacity is displayed by, for example, Microsoft Windows, it is reported as 372 GB, using a binary interpretation.

To address this ambiguity, the International System of Quantities standardizes the binary prefixes which denote a series of integer powers of 1024. With these prefixes, a memory module that is labeled as having the size 1GB has one gibibyte (1GiB) of storage capacity.


This 2.5 inch hard drive can hold 500 GB (i.e., 500 billion bytes) of data.

The term gigabyte is commonly used to mean either 10003 bytes or 10243 bytes. The latter binary usage originated as compromise technical jargon for byte multiples 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 International Electrotechnical Commission (IEC) published standards for binary prefixes, requiring that the gigabyte strictly denote 10003 bytes and gibibyte denote 10243 bytes. By the end of 2007, the IEC Standard had been adopted by the IEEE, EU, and NIST, and in 2009 it was incorporated in the International System of Quantities. 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 International System of Units (SI). This is the recommended definition by the International Electrotechnical Commission (IEC).[2] This definition is used in networking contexts and most storage media, particularly hard drives, flash-based storage,[3][4] and DVDs, and is also consistent with the other uses of the SI prefix in computing, such as CPU clock speeds or measures of performance. The file manager of Mac OS X version 10.6 and later versions are a notable example of this usage in software, which report files sizes in decimal units.[5]

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 operating systems, such as Microsoft Windows in reference to computer memory (e.g., RAM). This definition is synonymous with the unambiguous unit gibibyte.

Other Languages
Afrikaans: Gigagreep
العربية: جيجابايت
azərbaycanca: Giqabayt
বাংলা: গিগাবাইট
беларуская (тарашкевіца)‎: Гігабайт
bosanski: Gigabajt
català: Gigabyte
dansk: Gigabyte
español: Gigabyte
Esperanto: Gigabajto
euskara: Gigabyte
فارسی: گیگابایت
français: Gigabyte
한국어: 기가바이트
հայերեն: Գիգաբայթ
हिन्दी: गीगाबाइट
Bahasa Indonesia: Gigabita
italiano: Gigabyte
Jawa: Gigabita
ქართული: გიგაბაიტი
қазақша: Гигабайт
latviešu: Gigabaits
magyar: Gigabyte
македонски: Гигабајт
മലയാളം: ഗിഗാബൈറ്റ്
मराठी: गिगाबाईट
Bahasa Melayu: Gigabait
Nederlands: Gigabyte
日本語: ギガバイト
norsk: Gigabyte
norsk nynorsk: Gigabyte
پنجابی: گیگا بائٹ
polski: Gigabajt
português: Gigabyte
русский: Гигабайт
Scots: Gigabyte
sicilianu: Gigabyte
Simple English: Gigabyte
slovenčina: Gigabajt
slovenščina: Gigabajt
српски / srpski: Гигабајт
svenska: Gigabyte
татарча/tatarça: Гигабайт
తెలుగు: గిగాబైట్
тоҷикӣ: Гигабайт
Türkçe: Gigabayt
українська: Гігабайт
Tiếng Việt: Gigabyte
Winaray: Gigabyte
粵語: 吉字節
中文: 吉字节