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In January 1999, the International Electrotechnical Commission introduced in an addendum to IEC 60027-2 the prefixes kibi- (kibibyte), mebi-, gibi-, etc., and the symbols Ki, Mi, Gi, etc. to specify binary multiples of a quantity and eliminate the ambiguity with their SI meanings. Kibibit sounds a bit funny. Here is the new standard, but hardly anybody is using it: |
Name | Symbol | Before 1998 standardization | Name | After the standardization | ||||||
bit | b | 1 | bit | = | 1 bit | bit | 1 | b | = | 1 bit |
byte | B | 1 | B | = | 8 bit | byte | 1 | B | = | 8 bit |
kilobit | kbit / kb | 1 | kbit | = | 1024 b = bit | kilobit | 1 | kb | = | 1000 b |
kibibit | Kibit | kibibit | 1 | Kib | = | 1024 b | ||||
kilobyte | kB | 1 | kB | = | 1024 B = Byte | kilobyte | 1 | kB | = | 1000 B |
kibibyte | KiB | kibibyte | 1 | KiB | = | 1024 B | ||||
megabit | Mbit | 1 | Mbit | = | 1024 kb | megabit | 1 | Mb | = | 1000 kb |
mebibit | Mibit / Mib | mebibit | 1 | Mib | = | 1024 Kib | ||||
megabyte | MB | 1 | MB | = | 1024 kB | megabyte | 1 | MB | = | 1000 kB |
mebibyte | Mibit / MiB | mebibyte | 1 | MiB | = | 1024 KiB | ||||
gigabit | Gbit / Gb | 1 | Gbit | = | 1024 Mb | gigabit | 1 | Gb | = | 1000 MB |
gibibit | Gibit / Gib | gibibit | 1 | Gib | = | 1024 MiB | ||||
gigabyte | GB | 1 | GB | = | 1024 MB | gigabyte | 1 | GB | = | 1000 MB |
gibibyte | GiB | gibibyte | 1 | GiB | = | 1024 MiB | ||||
terabyte | TB | 1 | TB | = | 1024 GB | terabyte | 1 | TB | = | 1000 GB |
tebibyte | TiB | tebibyte | 1 | TiB | = | 1024 GiB | ||||
petabyte | PB | 1 | PB | = | 1024 TB | petabyte | 1 | PB | = | 1000 TB |
pebibyte | PiB | pebibyte | 1 | PiB | = | 1024 TiB | ||||
exabyte | EB | 1 | EB | = | 1024 PB | exabyte | 1 | EB | = | 1000 PB |
exbibyte | EiB | exbibyte | 1 | EiB | = | 1024 PiB | ||||
zettabyte | ZB | 1 | ZB | = | 1024 EB | zettabyte | 1 | ZB | = | 1000 EB |
zebibyte | ZiB | zebibyte | 1 | ZiB | = | 1024 EiB | ||||
yottabyte | YB | 1 | YB | = | 1024 ZB | yottabyte | 1 | YB | = | 1000 ZB |
yobibyte | YiB | yobibyte | 1 | YiB | = | 1024 ZiB |
1 Kibibyte [KiB] = 1024 = 210 Byte
1 Mebibyte [MiB] = 1 048 576 = 220 Byte
1 Gibibyte [GiB] = 1 073 741 824 = 230 Byte
1 Tebibyte [TiB] = 1 099 511 627 776 = 240 Byte
1 Pebibyte [PiB] = 1 125 899 906 842 624 = 250 Byte
1 Exbibyte [EiB] = 1 152 921 504 606 846 976 = 260 Byte
1 Zebibyte [ZiB] = 1 180 591 620 717 411 303 424 = 270 Byte
1 Yobibyte [YiB] = 1 208 925 819 614 629 174 706 176 = 280 Byte
1 Nobibyte [NiB] = 1 237 940 039 285 380 274 899 124 224 = 290 Byte
1 Dobibyte [DiB] = 1 267 650 600 228 229 401 496 703 205 376 = 2100 Byte
Old Definitions: 1 kb = (210) bits = 1 024 b 1 MB = (210)2 Bytes = 1 048 576 B To make the SI prefixes universal and to avoid confusion in the future, International Electrotechnical Commission (IEC), the leading international organization for worldwide standardization in electrotechnology, approved in December 1998 standard names and symbols of prefixes for binary multiples to be used in the fields of data processing and transmission. The prefixes are:
It is suggested that in English, the first syllable of the name of the binary-multiple prefix should be pronounced in the same way as the first syllable of the name of the corresponding SI prefix, and that the second syllable should be pronounced as "bee." Examples and comparisons with SI prefixes: 1 Kib = 210 bit = 1024 bit, 1 kb = 103 bit = 1000 bit, 1 MiB = 220 B = 1 048 576 B, 1 MB = 106 B = 1 000 000 B, 1 GiB = 230 B = 1 073 741 824 B, 1 GB = 109 B = 1 000 000 000 B. Based on the new definitions, the SI prefixes, k, M, and G, are back to their original meaning of 1 000, 1 000 000, and 1 000 000 000, respectively. The commonly known binary prefixes are written as Ki, Mi, and Gi and pronounced as kibi, mebi, and gibi, respectively. New Definitions: 1 kilo-bit = 1 kb = 103 bits = 1 000 b 1 kilo binary bit = 1 kibibit = 1 Kib = 210 bits = 1 024 b 1 mega byte = 1 MB = 106 Bytes = 1 000 000 B 1 mega binary byte = 1 mebibyte = 1 MiB = (210)2 B = 1 048 576 B The IEEE Standards Board decided that IEEE standards will be using the conventional, internationally adopted, definitions of the base-ten SI prefixes, except that the base-two definition may be used if such usage is explicitly pointed out on a case-by-case basis. |
Conversion: Transfer rates and bandwidths
byte = the well-established information measure unity
bit = the well-established data transfer unity
1 kilobit = 1 000 bits
1 megabit = 1 000 000 bits
Data of the hard disk are counted in kilobytes, however the transfer data rates are in kilobits.
Conclusion: A 56 k modem = 56 000 bits needs for transferring of
56 k data = 458 753 bits not 1 second, but at least 8.2 seconds.
This is confusing and you must always bear it in mind, when calculating transfer rates.
Rule of thumb : KByte of the data / seconds = transfer rate.
Connection | Theoretical rate in kb |
Optimal rate in kB |
Probable rate in kB |
14.4 modem | 14.4 kb/s | 1.2 kB/s | 1 kB/s |
28.8 modem | 28.8 kb/s | 2.4 kB/s | 2 kB/s |
33.6 modem | 33.6 kb/s | 3 kB/s | 2.5 kB/s |
56 k modem | 53 kb/s | 4.8 kB/s | 4 kB/s |
Single ISDN | 64 kb/s | 6 kB/s | 5 kB/s |
Dual ISDN | 128 kb/s | 12 kB/s | 10 kB/s |
DSL - light | 384 kb/s | 35 kB/s | 30 kB/s |
DSL | 1024 kb/s | 125 kB/s | 90 kB/s |
DSL | 2048 kb/s | 250 kB/s | 180 kB/s |
DSL | 3072 kb/s | 500 kB/s | 360 kB/s |
T1 | 1.54 Mb/s | 150 kB/s | 50 kB/s |
Cable modem | 6 Mb/s | 768 kB/s | 615 kB/s |
Intranet/LAN | 10 Mb/s | 1280 kB/s | 1024 kB/s |
100base-TLAN | 100 Mb/s | 12800 kB/s | 10240 kB/s |
The new IEC Standard | ||
Name | bit byte | |
bit | bit | 0 or 1 |
byte | B | 8 bits |
kibibit (binary) | Kib | 1024 bits |
kilobit (decimal) | kb | 1000 bits |
kibibyte (binary) | KiB | 1024 bytes |
kilobyte (decimal) | kB | 1000 bytes |
megabit (decimal) | Mb | 1000 kilobits |
mebibyte (binary) | MiB | 1024 kibibytes |
megabyte (decimal) | MB | 1000 kilobytes |
gigabit (decimal) | Gb | 1000 megabits |
gibibyte (binary) | GiB | 1024 mebibytes |
gigabyte (decimal) | GB | 1000 megabytes |
terabit (decimal) | Tb | 1000 gigabits |
tebibyte (binary) | TiB | 1024 gibibytes |
terabyte (decimal) | TB | 1000 gigabytes |
petabit (decimal) | Pb | 1000 terabits |
pebibyte (binary) | PiB | 1024 tebibytes |
petabyte (decimal) | PB | 1000 terabytes |
exabit (decimal) | Eb | 1000 petabits |
exbibyte (binary) | EiB | 1024 pebibytes |
exabyte (decimal) | EB | 1000 petabytes |
In data communications the metric definition of a kilobyte (1000 bytes per kilobyte) is correct. The binary definition of a kilobyte (1024 bytes per kilobyte) is used in areas such as data storage (harddisk, memory), but not for expressing bandwidth and throughput. |
File Storage Capacity by Bits and Bytes | |||||
bit | byte | kibibyte | mebibyte | gibibyte | |
bit | 1 | 0.125 | 0.000122070312 | 1.192092895×10-7 | 1.16415321875×10-10 |
byte | 8 | 1 | 0.0009765625 | 9.53674316×10-7 | 9.31322575×10-10 |
kibibyte | 8 192 | 1 024 | 1 | 0.0009765625 | 9.53674316×10-7 |
mebibyte | 8 388 608 | 1 048 576 | 1 024 | 1 | 0.0009765625 |
gibibyte | 8 589 934 592 | 1 073 741 824 | 1 048 576 | 1 024 | 1 |
tebibyte | 8 796 093 022 208 | 1 099 511 627 776 | 1 073 741 824 | 1 048 576 | 1 024 |
pebibyte | 9 007 199 254 740 990 | 1 125 899 906 842 624 | 1 099 511 627 776 | 1 073 741 824 | 1 048 576 |
exbibyte | 9 223 372 036 854 780 000 | 1 152 921 504 606 846 976 | 1 125 899 906 842 624 | 1 099 511 627 776 | 1 073 741 824 |
zebibyte | 9 444 732 965 739 290 000 000 | 1 180 591 620 717 411 303 424 | 1 152 921 504 606 846 976 | 1 125 899 906 842 624 | 1 099 511 627 776 |
CD: 2 × 44 100 × 16 = 1.4112 Mb/s : 8 b/B = 176.4 kb/s
2 × 44 100 × 20 = 1.764 Mb/s : 8 b/B = 220.5 kb/s
2 × 44 100 × 24 = 2.1168 Mb/s : 8 b/B = 264.6 kb/s
2 × 48 000 × 24 = 2.304 Mb/s : 8 b/B = 288.0 kb/s
These words are generally not totally accepted.
Units from Amendment 2 - International Standard IEC 60027-2
Prefix | Symbol | Power | Factor |
Yotta | Y | 1024 | 1 000 000 000 000 000 000 000 000 |
Zetta | Z | 1021 | 1 000 000 000 000 000 000 000 |
Exbi | Ei | 260 | 1 152 921 504 606 846 976 |
Exa | E | 1018 | 1 000 000 000 000 000 000 |
Pebi | Pi | 250 | 1 125 899 906 842 624 |
Peta | P | 1015 | 1 000 000 000 000 000 |
Tebi | Ti | 240 | 1 099 511 627 776 |
Tera | T | 1012 | 1 000 000 000 000 |
Gibi | Gi | 230 | 1 073 741 824 |
Giga | G | 109 | 1 000 000 000 |
Mebi | Mi | 220 | 1 048 576 |
Mega | M | 106 | 1 000 000 |
Kibi | Ki | 210 | 1 024 |
Kilo | k | 103 | 1 000 |
Reference unit | 100 | = 1 | 1 |
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