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Multiples of bytes
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
1024 KiB kibibyte KB kilobyte
10242 MiB mebibyte MB megabyte
10243 GiB gibibyte GB gigabyte
10244 TiB tebibyte
10245 PiB pebibyte
10246 EiB exbibyte
10247 ZiB zebibyte
10248 YiB yobibyte

The kibibyte is a multiple of the unit byte for quantities of digital information. The binary prefix kibi means 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.[citation needed]


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.[1][not in citation given]


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).[4] 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.[5][6][7]

See also[edit]


  1. ^ a b 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. ^ "What is a kilobyte?". Retrieved 2010-05-20. 
  5. ^ "Safier vs WDC complaint". Retrieved 2007-11-15. [dead link]
  6. ^ Grainger, Brian (7 August 2005). "I've got a bigger gigabyte than you!". Independent Computer Products Users Group (ICPUG). Retrieved 2007-11-15. 
  7. ^ 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.