Gigabytes to gibibytes (GB to GiB)

One gigabyte is exactly 0.9313225746 gibibytes. 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: 16 GB x 0.931322575 = 14.9012 GiB.

Going the other way, one gibibyte is 1.073741824 gigabytes.

For mental arithmetic: Multiply by 0.931, or take off about 7%.

A gigabyte is 10^9 bytes and a gibibyte is 2^30, which is 1,073,741,824, so a gigabyte is about 93.1% of a gibibyte. The gibibyte was standardized by the IEC in 1998 precisely to end this ambiguity, and adoption has been partial at best: Linux tools and RAM specifications use the binary units, drive marketing and most cloud billing use the decimal ones. RAM is the one place where the binary unit is genuinely natural, because memory is addressed in powers of two; storage never was.

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