How many gibibytes is a gigabyte?

How it works

Every unit is converted through bytes. A byte is 8 bits. The prefixes kilo, mega, giga and tera mean powers of 1,000: a gigabyte (GB) is 1,000,000,000 bytes. The binary prefixes kibi, mebi, gibi and tebi mean powers of 1,024: a gibibyte (GiB) is 2³⁰ = 1,073,741,824 bytes. So 1 GB is about 0.9313 GiB.

Drive makers use the 1,000-based units, so a 1 TB disk holds 1,000,000,000,000 bytes. Some operating systems count in 1,024s but still write GB, so the same disk shows about 931 “GB”, which is really 931 GiB. Nothing is missing.

The decimal prefixes come from the BIPM SI Brochure and the binary prefixes from IEC 80000-13, listed by NIST. Bit units (kbit, Mbit, Gbit) are 1,000-based, as network speeds use.