Pebibytes to petabytes (PiB to PB)

One pebibyte is exactly 1.125899907 petabytes. 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: 5 PiB x 1.12589991 = 5.6295 PB.

Going the other way, one petabyte is 0.8881784197 pebibytes.

For mental arithmetic: Multiply by 1.126, or add about an eighth.

A pebibyte is 2^50 bytes, 1,125,899,906,842,624, which makes it 12.6% larger than a decimal petabyte of 10^15. That is the widest gap yet between a binary unit and its decimal namesake, because the difference compounds at every step: 2.4% at kilo, 4.9% at mega, 7.4% at giga, 10% at tera and 12.6% at peta. At this scale it is a large amount of storage in its own right: the gap on a single PiB is about 126 TB.

Precision is worth matching to the input. A measurement given as 0.5 PiB carries one or two significant figures, and reporting its conversion to six implies a precision the original never had.