Kibibyte

Multiples of bytes
Decimal Value Metric 1000 kB kilobyte 1000^2 MB megabyte 1000^3 GB gigabyte 1000^4 TB terabyte 1000^5 PB petabyte 1000^6 EB exabyte 1000^7 ZB zettabyte 1000^8 YB yottabyte	Binary Value IEC JEDEC 1024 KiB kibibyte KB kilobyte 1024^2 MiB mebibyte MB megabyte 1024^3 GiB gibibyte GB gigabyte 1024^4 TiB tebibyte – 1024^5 PiB pebibyte – 1024^6 EiB exbibyte – 1024^7 ZiB zebibyte – 1024^8 YiB yobibyte –
Orders of magnitude of data

The kibibyte is a multiple of the unit byte for quantities of digital information. The binary prefix kibi means 2¹⁰, or 1024, therefore 1 kibibyte is 1024 bytes. The unit symbol for the kibibyte is KiB.^[1]

The unit was established by the International Electrotechnical Commission (IEC) in 1998,^[2] has been accepted for use by all major standards organizations, and is part of the International System of Quantities.^[3] The kibibyte was designed to replace the kilobyte in those computer science contexts in which the term kilobyte is used to mean 1024 bytes. The interpretation of the kilobyte to denote 1024 bytes, conflicting with the SI definition of the prefix kilo (1000), is still common, mostly in informal computer science contexts.

Definition

1 kibibyte = 2¹⁰ bytes = 1024 bytes.

The prefix kibi is derived as a portmanteau of the words kilo and binary, indicating its origin in the closeness in value to the SI prefix kilo (1000). While the SI prefix is written with lowercase (k), all IEC binary prefixes use an uppercase letter.^[4]

History

The kibibyte is closely related to the kilobyte. The latter term is often used in some contexts as a synonym for kibibyte, but formally refers to 10³ bytes = 1000 bytes, as the prefix kilo is defined in the International System of Units.

The binary interpretation of the metric prefixes causes relatively small differences with the smallest prefixes in the series, i.e. for kilo and mega, but grows to substantial differences beyond.

Donald Knuth proposed to call this unit a large kilobyte (KKB).^[5] Other early proposals included using the Greek lowercase letter κ (kappa) for 1024 bytes (and using k exclusively for 1000), bK, KB, and others.

IEC binary prefixes are increasingly used, especially in scientific literature and open source software. In product advertising and other non-scientific publications, the kilobyte sometimes refers to a power of ten and sometimes a power of two.^[6][7][8]

See also

• IEC 80000-13
• IEEE 1541
• Timeline of binary prefixes

References

1. International Electrotechnical Commission (2007). "Prefixes for binary multiples". Retrieved 2014-01-09.
2. International Electrotechnical Commission (January 1999), IEC 60027-2 Amendment 2: Letter symbols to be used in electrical technology - Part 2: Telecommunications and electronics
3. "IEC 80000-13:2008". International Organization for Standardization. Retrieved 2013-07-21.
4. National Institute of Standards and Technology. "Prefixes for binary multiples". Retrieved 2015-10-09.
5. "What is a kilobyte?". Retrieved 2010-05-20.
6. "Safier vs WDC complaint". WesternDigital.com. Archived from the original on October 16, 2007. Retrieved 2007-11-15.
7. Grainger, Brian (7 August 2005). "I've got a bigger gigabyte than you!". Independent Computer Products Users Group (ICPUG). Retrieved 2007-11-15.
8. Barry Wittman; Aditya Mathur; Tim Korb (30 December 2012). Start Concurrent: An Introduction to Problem Solving in Java with a Focus on Concurrency, 2013 Edition. Purdue University Press. p. 5. ISBN 978-1-55753-672-3. Retrieved 1 May 2013.