Kibibyte

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

The unit was established by the International Electrotechnical Commission (IEC) in 1998^[2] and has been accepted for use by all major standards organizations. It was designed to replace the kilobyte where used to mean 1024 bytes. Such use, which conflicts with the SI definition of the prefix kilo, is common in some 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), the IEC prefix uses an uppercase letter.

History

The kibibyte is closely related to the kilobyte. The latter is often used in some contexts as a synonym for the kibibyte, but formally refers to 10³ bytes = 1000 bytes, as the prefix 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 (see binary prefix: deviation between powers of 1024 and powers of 1000).

In Introduction to MMIX, Donald Knuth proposed that this unit be called a large kilobyte (abbreviated KKB).^[3] Other early proposals included using the Greek lowercase letter κ (kappa) for 1024 bytes (and using k exclusively for 1000), bK, KB, and others. See binary prefix: early suggestions.

Binary prefixes are increasingly used 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.^{[4][5] [6]}

See also

• Kilobyte
• IEEE 1541
• IEC 80000-13

References