Kilobytes to Kibibytes (kB to KiB)

1 kilobyte equals 0.9765625 kibibytes exactly.

How to convert kilobytes to kibibytes

To convert kilobytes to kibibytes, multiply the number of kilobytes by 0.9765625. This factor is exact. To go the other way, multiply kibibytes by 1.024.

kibibytes = kilobytes × 0.9765625

Example: 10 kilobytes = 9.765625 kibibytes.

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

Kibibyte (KiB)

ComputingCurrent unit

Exactly 1,024 bytes (2¹⁰). The IEC name for the binary kilobyte, used by operating systems and memory specifications.

Kibibyte is the first of the names the IEC approved in December 1998 for binary multiples, built from kilobinary. The IUPAC's Interdivisional Committee on Nomenclature and Symbols had proposed binary prefixes in 1995, and the IEC published them in January 1999. The symbol KiB adds an i to the SI symbol, with the K capitalized. NIST says the names keep the first two letters of each SI prefix and add bi, to signal binary.

One KiB is exactly 1,024 bytes, about 2.4 percent more than a kilobyte. The standard is now IEC 80000-13, supported by the BIPM, IEC and NIST. In practice the symbols are rarely used outside a few places such as KDE and Qt-based applications, which can switch between SI and binary units. Donald Knuth jokingly suggested in 1999 calling it a large kilobyte, KKB.

1 kibibyte = 1,024 bytes (exactly).

Sources: NIST: Prefixes for binary multiples; Wikipedia: Kibibyte

Related conversions

See all digital storage units.