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A gigabyte (derived from the SI prefix giga-) is a unit of information or computer storage equal to one billion (that is, a thousand million) bytes.

Definition

There are two slightly different definitions of the size of a gigabyte in use:

• 1,000,000,000 bytes or 10 bytes is the decimal definition used in telecommunications (such as network speeds) and most computer storage manufacturers (such as hard disks and flash drives). This usage is compatible with SI. Quotes from Seagate: "The storage industry standard is to display capacity in decimal", and "One gigabyte, or GB, equals one billion bytes when referring to hard drive capacity", and similar quotes are found on the websites of other storage manufacturers.
• 1,073,741,824 bytes, equal to 1024, or 2 bytes. This is the definition used for computer memory sizes, and most often used in computer engineering, computer science, and most aspects of computer operating systems. The IEC recommends that this unit should instead be called a gibibyte (abbreviated GiB), as it conflicts with SI units used for bus speeds and the like. HP states that Microsoft normally adheres to this definition

About its name

It is commonly abbreviated GB in writing (not to be confused with Gb, which is used for gigabit)

Gigabyte is often informally abbreviated to gig, as in "This is a three hundred gig hard drive".

In English the initial G of giga- can be pronounced with a soft G as in gene, or with a hard G as in giggle. The latter hard G pronunciation has become more common.

Gigabytes vs gigabits

In conventional modern usage, a byte is 8 bits. One gigabyte is equivalent to eight gigabits.

Gigabytes in use

Facts

• As of 2006, most consumer hard drives are defined by their gigabyte-range capacities. The true capacity is usually some number above or below the class designation. Although most hard disk manufacturers' definition of GB is 1,000,000,000 bytes (however, computer memory has a natural inclination towards units that are powers of 2), most computer operating systems use the 1,073,741,824 byte definition. This distinction can be a cause of confusion, especially for people from a non-technical background, as a hard disk with a capacity of 1,000,000,000 bytes would have a reported capacity of only 0.93 GB.

Gigabytes in different products

• A DVD-5 format disc is capable of storing 4.7 gigabytes, or roughly 4.38 gibibytes. A DVD-9 is capable of storing 8.5 gigabytes, or roughly 7.92 gibibytes.
• One gigabyte is roughly equal to 18 hours of MP3 music (at 128 kbit/s).
• One gigabyte is roughly equivalent to 11 hours, 40 minutes of Flash video (at 450x370).
• Most 6th generation game consoles have game discs that are around 1 GB or more: Dreamcast (1.1 GB), GameCube (1.5 GB), Playstation 2 (8.5 GB), and Xbox (8.5 GB)
• The human genome contains 0.791175 GB of data (the 3.1647×10 base pairs represented as 2-bits).

See also

• Gibibyte
• Gigabit
• Binary prefix
• Orders of magnitude (data)

Notes

External links

• http://physics.nist.gov/cuu/Units/binary.html
• http://www.iec.ch/zone/si/si_bytes.htm
• http://www.quinion.com/words/turnsofphrase/tp-kib1.htm
• http://www.nist.gov/public_affairs/techbeat/tb9903.htm

• Units of information