Dezimalzahlen gegen Binärzahlen oder 10 gegen 2

Decimal vs Binary, base 10 values vs base 2 values. (by Jack B. Korten)

When you purchase a 1 terabyte hard drive, you will find that it holds only 931 gigabytes. What happened to the missing 69 gigabytes?

The prefixes kilo, mega, giga, tera etc.. belong to the International System of Units (SI) which uses a decimal system with base 10 values.

kilo       103      from Greek "chilioi" meaning 'thousand' (10001)

mega   106      from Greek "megas" meaning 'great', 'large'

giga     109      from Greek "gigas" meaning ‘giant’.

tera      1012    from Greek "teras", meaning 'monster'.

peta     1015    from Greek "penta" meaning five (10005)

exa      1018    from Greek "hex" meaning ‘six’.

zetta    1021 from Latin "septem" meaning seven, p dropped, first letter changed to z

yotta    1024    from Latin "octo" meaning eight, y added, c dropped.

Computers use a binary system with a base value of 2. The prefixes kilo, mega, giga, etc. are decimal prefixes and are out of step with binary values. Hard drive manufacturers take advantage of this ambiguity, so they inflate the sizes of their hard drives.

The difference between the two systems has always been an annoyance, but now the discrepancies have become difficult to ignore, because of today's enormous hard drives.

In December 1998, the IEC (International Electrotechnical Commission) addressed this problem by creating prefixes such as kibi, mebi, gibi, etc., denoting powers of 1024. Thus the kibibyte, symbol KiB, represents 210 = 1024 bytes.

These prefixes are now part of the International System of Quantities.

Below, a comparison of the two systems:


kilobyte           KB       103      1000                           kibibyte           KiB      210       1024

megabyte        MB       106      10002                         mebibyte         MiB      220       10242

gigabyte          GB       109      10003                         gibibyte           GiB      230       10243

terabyte          TB       1012        10004                        tebibyte           TiB       240       10244

petabyte         PB       1015    10005                           pebibyte          PiB       250       10245

exabyte          EB       1018     10006                          exbibyte          EiB       260       10246

zettabyte        ZB       1021        10007                         zebibyte          ZiB      270       10247

yottabyte        YB       1024     10008                           yobibyte          YiB      280       10248

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