Gibibytes

The gibibyte is a multiple of the unit byte for digital information. The binary prefix gibi means 2³⁰, therefore one gibibyte is equal to 1073741824bytes = 1024 mebibytes. The unit symbol for the gibibyte is GiB. It is one of the units with binary prefixes defined by the International Electrotechnical Commission (IEC).

The gibibyte is very closely related to the gigabyte (GB). The GB is defined by the IEC as 10⁹ bytes = 1000000000bytes, 1GiB ≈ 1.074GB. 1024 gibibytes are equal to one tebibyte. In the context of computer memory, Gigabyte and GB are customarily used to mean 1024³ (2³⁰) bytes, although not in the context of data transmission and not necessarily in the context of hard drive size. The word gibibyte was coined in 1998.

Hard drive and SSD manufacturers use "GB" to mean 1000000000 bytes. So, the capacity of a "128 GB" SSD will be 128000000000 bytes. Expressed in GiB this would be about 119.2 GiB (128000000000 divided by 1073741824). Many operating systems, including Microsoft Windows, will display such a drive's capacity as "119 GB", using the SI prefix "G" but in the "binary" sense. No space is "lost" or "missing". The size is simply being expressed in a different unit, even though the "G" prefix is used in both cases.

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