Kibibytes to kilobytes (KiB to kB)

One kibibyte is exactly 1.024 kilobytes. That is the definition of the prefixes, not a measurement: the decimal SI prefixes (kilo, mega, giga, tera) step by exactly 1,000, and the binary IEC prefixes (kibi, mebi, gibi, tebi) step by exactly 1,024. The two families are both exact; the trouble is only that software and storage labels do not always say which one they mean.

Worked through: 64 KiB x 1.024 = 65.536 kB.

Going the other way, one kilobyte is 0.9765625 kibibytes.

For mental arithmetic: Multiply by 1.024, or add 2.4%.

A kibibyte is 1,024 bytes and a kilobyte 1,000, so one KiB is 1.024 kB, a gap of 2.4%, the smallest of the binary-versus-decimal gaps. KiB is the unit of the small, fixed blocks a computer works in: a memory page and a modern disk sector are both 4 KiB, which is 4,096 bytes, and Linux tools such as du and ls -lh print K meaning KiB. The confusion is that KB written with a capital K was used for decades to mean 1,024 bytes, so a figure labeled KB can be either unit.

Precision is worth matching to the input. A measurement given as 1 KiB carries one or two significant figures, and reporting its conversion to six implies a precision the original never had.