Kilobytes to Kilobits (kB to kb)

1 kilobyte equals 8 kilobits exactly.

How to convert kilobytes to kilobits

To convert kilobytes to kilobits, multiply the number of kilobytes by 8. This factor is exact. To go the other way, multiply kilobits by 0.125.

kilobits = kilobytes × 8

Example: 10 kilobytes = 80 kilobits.

Decimal prefixes (kB, MB, GB) are powers of 1,000; binary prefixes (KiB, MiB, GiB) are powers of 1,024. Storage makers use decimal; Windows reports binary but labels it GB.

About these units

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.

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.

1 kilobyte = 1,000 bytes (exactly).

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

Kilobit (kb)

ComputingCurrent unit

1,000 bits (125 bytes). Used for data rates and sizes in telecommunications.

Kilobit means a thousand bits, and in telecommunications data rates are usually measured in decimal SI multiples. The article on the bit gives a handy example: a channel capacity of 8 kbit/s is 1 kB/s, so dividing kilobits by eight gives kilobytes. The binary counterpart, the kibibit, is 1,024 bits, but it is seldom used.

Symbols cause trouble. The IEC standard says to write kbit, while IEEE 1541-2002 recommends a lowercase b, giving kb, and the lowercase b may be confused with capital B for byte. On this site a kilobit is 125 bytes. The history behind it is that of the bit itself: Ralph Hartley proposed a logarithmic information measure in 1928, and Claude Shannon first used the word in 1948, crediting John W. Tukey.

1 kilobit = 125 bytes (exactly).

Sources: Wikipedia: Bit; Wikipedia: Kilobit

Related conversions

See all digital storage units.