A kilobyte (derived from the SI prefix kilo-) is a unit of information or computer storage equal to one thousand bytes. It is commonly abbreviated KB in writing and K in writing or speech.

Two definitions of the kilobyte are in common use:

• 1,000 bytes (10³): This definition is consistent with the SI prefix and most other uses of the prefix in computing.
• 1,024 bytes (2¹⁰): This definition is used to express memory capacity and by most software to express storage capacity. This quantity may be expressed unambiguously as a kibibyte (see binary prefixes).

byte << kilobyte << megabyte