In 1999, the International Electrotechnical Commission (IEC) published Amendment 2 to “IEC 60027-2: Letter symbols to be used in electrical technology – Part 2: Telecommunications and electronics”;. This standard, which had been approved in 1998, introduced the prefixes kibi-, mebi-, gibi-, tebi-, pebi-, exbi-, to be used in specifying binary multiples of a quantity. The names come from the first two letters of the original SI prefixes followed by bi which is short for “binary”. It also clarifies that, from the point of view of the IEC, the SI prefixes only have their base-10 meaning and never have a base-2 meaning.
So this is the correct usage for file, disk, memory size:
Kilobytes (KB) 1.000 Kibibyte (KiB) 1024
Megabyte (MB) 1.000 ^ 2 Mebibyte (MiB) 1024 ^ 2
Gigabyte (GB) 1.000 ^ 3 Gibibyte (GiB) 1024 ^ 3
Terabyte (TB) 1.000 ^ 4 Tebibyte (TiB) 1024 ^ 4
Petabyte (PB) 1.000 ^ 5 Pebibyte (PiB) 1024 ^ 5
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