Gigabyte: Difference between revisions

This article is about the unit of measurement. For the computer hardware manufacturer, see Gigabyte Technology.

Multiple-byte units
Decimal Value Metric 1000 kB kilobyte 10002 MB megabyte 10003 GB gigabyte 10004 TB terabyte 10005 PB petabyte 10006 EB exabyte 10007 ZB zettabyte 10008 YB yottabyte 10009 RB ronnabyte 100010 QB quettabyte	Binary Value IEC Memory 1024 KiB kibibyte KB kilobyte 10242 MiB mebibyte MB megabyte 10243 GiB gibibyte GB gigabyte 10244 TiB tebibyte TB terabyte 10245 PiB pebibyte – 10246 EiB exbibyte – 10247 ZiB zebibyte – 10248 YiB yobibyte – 10249 – – 102410 – –
Orders of magnitude of data

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

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

• 1,000,000,000 bytes or 10⁹ 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.
• 1,073,741,824 bytes, equal to 1024³, or 2³⁰ 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.

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

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

Gigabytes in use

• 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 (only 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 cause confusion.
• As of 2006, consumer hard drive per-gigabyte costs are 0.20-0.80 USD.
• In speech, gigabyte is often informally abbreviated to gig, as in "This is a ten-gig hard drive".
• A DVD-5 format disc is capable of storing 4.7 GB (4.38 GB in prefix).
• One gigabyte is roughly equal to 18 hours of MP3 music (at 128 kbit/s).
• The human genome contains 6.3294 GB of data (the 3.1647×10⁹base pairs[1] represented as 2-bits).
• Most USB flash drives have a capacity measured in megabytes (MB), but flash drives with capacities greater than 1 GB have been released recently.
• Most 6th generation game consoles have game discs that are around 1GB or more: Dreamcast(1.1 GB),GameCube(1.5 GB),Playstation 2(8.5GB), and XBox(8.5 GB)

See also

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

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