What is a binary prefix

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Kilobytes and Kibibytes: binary prefixes

Binary prefix

symbol

importance

conversion

kibi

KiB

2^10

1 kibibyte = 1.02 kilobytes

mebi

MiB

2^20

1 mebibyte = 1.05 megabytes

gibi

GiB

2^30

1 gibibyte = 1.07 gigabytes

tebi

TiB

2^40

1 tebibyte = 1.10 terabytes

pebi

PiB

2^50

1 pebibyte = 1.13 petabytes

How big is a data carrier? It always depends on which program you ask. Because although the displayed size units of the Linux kernel follow the IEC standards, programs such as file managers sometimes use the decimal units for bytes and sometimes the binary. So it happens that a USB stick with eight GB (decimal) only has 7.45 GB (binary) elsewhere.

Computer science works with the binary system and thus with powers of two: A kilobyte is therefore not 10³ bytes, but 210 bytes. Nevertheless, one program calculates in powers of ten and the other in powers of two. And both use the same size prefixes with Kilo, Mega, Giga, Tera. These prefixes are binding for a decimal base in the "Système International d'Unités". Strictly speaking, the use of binary units is not permitted and causes confusion. At the suggestion of the IEEE, the International Electrotechnical Commission therefore developed its own system of designations for binary units of measurement at the end of the 1990s, based on the SI system. The prefixes are each given the appended syllable "bi" for binary. 1024 bytes are no longer a kilobyte, but a kibibyte. This correct nomenclature has also partially found its way into Linux: The kernel messages that you receive with the command dmesg show disk sizes in Kibibyte (KiB), Mebibyte (MiB) and Gigibyte (GiB). The partitioner Gparted also works with these sizes and thus eliminates all inaccuracies.

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