View source for Kilobyte

===Binary (1024&nbsp;bytes)===
The term ''kilobyte'' has traditionally been used to refer to 1024&nbsp;bytes (2<sup>10</sup>&nbsp;B).<ref>[http://www.merriam-webster.com/dictionary/kilobyte Kilobyte – Definition and More from the Free Merriam-Webster Dictionary] {{webarchive|url=https://web.archive.org/web/20100409171320/http://www.merriam-webster.com/dictionary/kilobyte |date=2010-04-09 }}. Merriam-webster.com (2010-08-13). Retrieved on 2011-01-07.</ref><ref>[http://dictionary.reference.com/browse/kilobyte Kilobyte | Define Kilobyte at Dictionary.com] {{webarchive|url=https://web.archive.org/web/20100901202451/http://dictionary.reference.com/browse/kilobyte |date=2010-09-01 }}. Dictionary.reference.com (1995-09-29). Retrieved on 2011-01-07.</ref><ref>[http://www.askoxford.com/concise_oed/kilobyte?view=uk Definition of kilobyte from Oxford Dictionaries Online] {{webarchive|url=https://web.archive.org/web/20060625132017/http://www.askoxford.com/concise_oed/kilobyte?view=uk |date=2006-06-25 }}. Askoxford.com. Retrieved on 2011-01-07.</ref> The usage of the metric prefix ''kilo'' for binary multiples arose as a convenience, because 1024 is approximately 1000.<ref>{{cite web|title=Prefixes for binary multiples|url=http://www.iec.ch/si/binary.htm|website=iec.ch|publisher=International Electrotechnical Commission|access-date=1 October 2016|url-status=live|archive-url=https://web.archive.org/web/20160925125914/http://www.iec.ch/si/binary.htm|archive-date=25 September 2016}}</ref>

The binary interpretation of metric prefixes is still prominently used by the [[Microsoft Windows]] operating system.<ref name="auto">{{cite web |url=http://support.microsoft.com/kb/121839 |title=Determining Actual Disk Size: Why 1.44 MB Should Be 1.40 MB |publisher=Support.microsoft.com |date=2003-05-06 |access-date=2014-03-25 |url-status=live |archive-url=https://web.archive.org/web/20140209012305/http://support.microsoft.com/kb/121839 |archive-date=2014-02-09 }}</ref> Binary interpretation is also used for [[random-access memory]] capacity, such as main memory and [[CPU cache]] size, due to the prevalent [[binary address]]ing of memory.

The binary meaning of the kilobyte for 1024&nbsp;bytes typically uses the symbol KB, with an uppercase letter ''K''. The ''B'' is sometimes omitted in informal use. For example, a processor with 65,536&nbsp;bytes of cache memory might be said to have "64&nbsp;K" of cache. In this convention, one thousand and twenty-four kilobytes (1024&nbsp;KB) is equal to one megabyte (1&nbsp;MB), where 1&nbsp;MB is 1024<sup>2</sup>&nbsp;bytes.

In December 1998, the [[International Electrotechnical Commission|IEC]] addressed such multiple usages and definitions by creating prefixes such as kibi, mebi, gibi, etc., to unambiguously denote powers of 1024.<ref>{{cite web|url=http://physics.nist.gov/cuu/Units/binary.html|title=Prefixes for binary multiples|author=National Institute of Standards and Technology|author-link=National Institute of Standards and Technology|url-status=live|archive-url=https://web.archive.org/web/20070808000831/http://physics.nist.gov/cuu/Units/binary.html|archive-date=2007-08-08}} "In December 1998 the [[International Electrotechnical Commission]] (IEC) [...] approved as an IEC International Standard names and symbols for prefixes for binary multiples for use in the fields of data processing and data transmission."</ref> Thus the kibibyte, symbol KiB, represents 2<sup>10</sup>&nbsp;bytes = 1024&nbsp;bytes. These prefixes are now part of IEC 80000-13. The IEC further specified that the kilobyte should only be used to refer to 1000&nbsp;bytes.  The [[International System of Units]] restricts the use of the SI prefixes strictly to powers of 10.<ref>{{SIbrochure9th|page=143}}. "The SI prefixes refer strictly to powers of 10. They should not be used to indicate powers of 2 (for example, one kilobit represents 1000&nbsp;bits and not 1024&nbsp;bits). The names and symbols for prefixes to be used with powers of 2 are recommended as follows: kibi Ki 2<sup>10</sup> [...]"</ref>