Storage capacity

the storage capacity is the altogether available storage location of a data structure or a storage medium.

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storage capacity in the data processing

the extentin the unit bit is measured by data or information in the sense of the communication theory. 8 bits become the basic unit byte (originally byte stood for a system dependent number of bits, 8 bits also as a Oktett was designated, however are todaynearly only 7 - and 8-bit bytes common, 7-Bit-Bytes also only in the data communication). Mostly with byte 1 Oktett, thus 8 bits, is summarized, on which the next higher units develop. Due to the original definition of a kilobyte also1024 instead of 1000 byte can come it to different counting methods (see under data set).


  • 1 bit - (2 1 = 2 possible conditions), z. B. 0/1
  • 5 bits - (2 5 = 32 possible conditions), z. B. a capital letterfrom latin alphabet
  • 7 bits - (2 7 = 128 possible conditions), z. B. an indication in the ASCII - character set

Nibble or half byte

  • 1 Nibble - (2 4 = 16 possible conditions), z. B. 0/1/2/… /15
  • 2 Nibble - (2 8= 256 possible conditions), thus 1 byte

byte or Oktett (8-bit)

  • 1 Oktett - (2 8 = 256 possible conditions) a character in the ANSI coding (extended latin alphabet)
  • 2 Oktett - (2 16 = 65,536 possible conditions)Character in the UTF-16 - format
  • 4 Oktett - (2 32 = about 4.3 billion possible conditions)

kilobyte (KB) (10 3 byte = 1000 byte),
Kibibyte (KiB) (2 10 byte = 1024 byte), becomes frequent instead also KB for the distinction of KB written.

  • approx. 0.5 KB - a book side as text
  • 1440 KiB - a High Density 3.5 tariff disk

megabyte (MT) (10 6 byte = 1.000.000 byte),
Mebibyte (MIB) (2 20 byte = 1.048.576 byte)

  • approx. 5 MT - the Bible as text
  • approx. 703.1 MIB thus approx. 737.8 MT - conventional “700 MT” a data CD-ROM

gigabyte (GB) (10 9 byte = byte),
Gibibyte (give) (2 30 byte = 1,073,741,824 byte)

  • approx. 4,38 give thus approx.4.7 GB - a DVD±R
  • approx. 5 GB - a compressed feature in DVD quality

Terabyte (TB) (10 12 byte = 1000 GB),
Tebibyte (TiB) (2 40 byte)

  • approx. 20 TB text extent of the existence of the LIBRARY OF Congress with approximately 20Millions books (1963 - might lie in the meantime with up to 80 TB)

Petabyte (PB) (10 15 byte = 1.000.000 GB),
Pebibyte (PiB) (2 50 byte)

  • the storage capacities of the world-wide largest computing centres were appropriate for at the end of of 2002 between 1 PB and 10 PB

Exabyte (EB) (10 18 byte),
Exbibyte (EiB) (2 60 byte)

  • the whole of all printed works becomes on 0,2 EB estimated

Zettabyte (E.G.) (10 21 byte),
Zebibyte (ZiB) (2 70 byte)

Yottabyte (YB) (10 24 byte),
Yobibyte (YiB) (2 80 byte)

  • 1 YB are about as much byte, as atoms in 1,67 gram hydrogen, according to 0.83 mol of H 2, are present.

Binary designations

the binary prefixes serve for the fact that one ensures on the one hand the correct use of the unit prefixes andon the other hand frequent used sizes 2 the 10, 2 20 etc. as unit to be formulated.

data media

with the indication of capacity of non removable disks become usually of the manufacturers according to the SI standard 10er-Potenzen (z. B. Gigabyte) uses. Butsince memory requirements are usually indicated by programs and operating systems in Gibibyte, confusion often arises. Thus z becomes. B. 20 GB a large non removable disk by the operating system only as 18.6 „GB “largely indicated, because 20 GB are approximately 18.6 give. Therefore the binary prefixes and their abbreviations should be always used according to (International Electronical Commission) in new programs either, or both data should be represented. To note furthermore it is that the size of the disk free space actually in a computer ofrespective file system depends.

„Historical accident “one can call the usual statements of size with disks: On a 720-KiB-Diskette 720 fits · 1024 byte. When the capacity was then doubled, one called these however not „1440-KiB-Diskette “, but falsely „1,44-MB-Diskette “. There their capacityhowever 1,44 · 1000 · 1024 byte amount to, act it here thus neither by 1,44 megabyte nor around 1,44 Mebibyte, but rather around 1,44 „Kilokibibyte “.


goods it in former times primarily non removable disk manufacturer, those their storage capacities„fälscherlicherweise “more largely indicated by the multiplication to the basis 10 (kilo=1000) instead of - as it was rather usual - to the basis 2 (kilo=1024), there is in contrast to it today many software producers, who do not use the new binary prefixes or inkonsequent, because thesemostly counted contrary to various hardware manufacturers on 2er and not on 10er-Potenzen.

When that should have exerted internationally Electrotechnical Commission (International Electronical Commission) accused criticism at the binary prefixes, it pressure on hardware manufacturers, megabyte, gigabyte and Terabyte etc. the old quasi-standardto convert according to also with 2er-Potenzen, instead of introducing new prefixes and to redefine thus the old since the 1960er years existing designations all, which leads to confusion.

It is answered to that that on the one hand it already before the introduction of the binary prefixes 1998 no uniformPrefix use in the IT-industry gave (the extreme example of the 1,44-Disketten mentioned already above), but manufacturers often only for market-technical reasons for or other use of the ambiguous prefixes would have decided and this also further would do. Besidesgo it not around preferring any industries using prefixes in the long term but uniform (thus not ambiguous) around the straight existing confusion to avoid. There the Greek prefixes Kilo, mega, giga etc. already for 10er-Potenzen were reserved, is the introduction of new prefixes inevitably been. The transition-moderate easy increase of the confusion resulting from it would put, as soon as the new prefixes would achieve a certain admitting heating degree and one had gotten accustomed to it.

Confusion gives way it so far - also yearthe introduction of the new prefix still. So for example 700 MB-CD have approx. 700 MIB (=700 · 1024 · 1024 byte) capacity, 4.7 GB-DVD against it actually approx. 4.7 GB (thus 4,7 · 1000 · 1000 · 1000 byte),which in approximately 4.38 give corresponds.
Since soft and hardware manufacturers change over only very zögerlich to the binary prefixes, an end of the confusion is not yet in view. It is to be accepted that the old binary prefixes remain likewise decades in use like calorie and HP.

see also

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