When browsing the CiA Product Guides, you will perhaps wonder about the units of e.g. RAM, when you read 1 KiB. This (kibibyte) is the official prefix for 1 024 byte according to IEC 60027-2. As "kilo" only defines an amount of 1 000, the use of this prefix is - in theory - incorrect.

In December 1998 the International Electrotechnical Commission (IEC) approved as an IEC International Standard names and symbols for prefixes for binary multiples for use in the fields of data processing and data transmission. The prefixes are as follows:

Prefixes for binary multiples


 Factor 

Name 

Symbol 

Origin

Derivation 

 210

kibi

Ki

kilobinary: (210)1

kilo: (103)1

 220

mebi

Mi

megabinary: (210)

mega: (103)2

 230

gibi

Gi

gigabinary: (210)3

giga: (103)3

 240

tebi

Ti

terabinary: (210)4

tera: (103)4

 250

pebi

Pi

petabinary: (210)5

peta: (103)5

 260

exbi

Ei

exabinary: (210)6

exa: (103)6


Examples and comparisons with SI prefixes

one kibibit

 1 Kibit = 210 bit = 1024 bit

one kilobit

 1 kbit = 103 bit = 1000 bit

one mebibyte

 1 MiB = 220 B = 1 048 576 B

one megabyte

 1 MB = 106 B = 1 000 000 B

one gibibyte

 1 GiB = 230 B = 1 073 741 824 B

one gigabyte

 1 GB = 109 B = 1 000 000 000 B