Kilobyte (kB)

ComputingCurrent unit

1,000 bytes in the SI (decimal) definition. Older software and Windows sometimes use KB to mean 1,024 bytes; see kibibyte.

1 kilobyte = 1,000 bytes (exactly).

1 kilobyte = 1,000 bytes

About the kilobyte

Few units have had two meanings for so long. By the mid-1960s most computers used binary addressing, so memory sizes came in powers of two and engineers borrowed kilo to mean 1,024. IBM documentation for the System/360 in 1964 used an uppercase K for 1,024. Hard disk makers took a different path from the start. The IEC later settled the question: kilobyte, symbol kB, means 1,000 bytes, and 1,024 bytes is a kibibyte.

Floppy disks show the muddle. The Shugart SA-400 of 1976 held 109,375 bytes unformatted and was advertised as 110 Kbyte, the decimal way, while a 1978 Tandon double-density disk held 368,640 bytes, or 360 times 1,024, and was sold as 360 KB. Windows still divides by 1,024, so a 65,536-byte file appears as 64 KB there, while Mac OS X Snow Leopard and later would call it 66 kB. A kilobyte is also tiny: Edgar Allan Poe's The Cask of Amontillado is 12,843 bytes.

Sources: Wikipedia: Kilobyte; Wikipedia: Binary prefix; NIST: Prefixes for binary multiples

Kilobyte conversion chart

1 kilobyte expressed in every other digital storage unit:

Unit1 kilobyte
Bytes1,000
Megabytes0.001
Gigabytes0.000001
Terabytes1×10⁻⁹
Bits8,000
Petabytes1×10⁻¹²
Kibibytes0.9765625
Mebibytes0.0009536743164
Gibibytes9.313225746×10⁻⁷
Tebibytes9.094947018×10⁻¹⁰
Kilobits8
Megabits0.008
Gigabits0.000008
Exabytes1×10⁻¹⁵
Zettabytes1×10⁻¹⁸
Yottabytes1×10⁻²¹
Pebibytes8.881784197×10⁻¹³
Exbibytes8.67361738×10⁻¹⁶
Terabits8×10⁻⁹
Kibibits7.8125
Mebibits0.007629394531
Gibibits0.000007450580597
Nibbles2,000

More Computing units

All Computing units

Browse all digital storage units.