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Bit and Byte Conversion Calculator

Type values into the field.

Decimal (SI prefixes)Binary (SI prefixes)Binary IEC
kilobitkb, kbitkilobitKb, KbitkibibitKibit
megabitMb, MbitmegabitMb, MbitmebibitMibit
gigabitGb, GbitgigabitGb, GbitgibibitGibit
terabitTb, TbitterabitTb, TbittebibitTibit
petabitPb, PbitpetabitPb, PbitpebibitPibit
exabitEb, EbitexabitEb, EbitexbibitEibit
zettabitZb, ZbitzettabitZb, ZbitzebibitZibit
yottabitYb, YbityottabitYb, YbityobibitYbit

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bit (bit, b)

A bit is the basic unit of information in computing and telecommunications; it is the amount of information that can be stored by a device and can normally exist in only two distinct states. A bit can also be defined as a variable or computed quantity that can have only two possible values. These two values are often interpreted as binary digits and are usually denoted by digits 0 and 1. ISO/IEC IEC 80000-13:2008 specifies that the symbol for bit should be "bit", though the letter "b" (in lower case) is still widely used.

byte (B) also octet(o)

A byte or octet is a unit of memory or data equal to the amount used to represent one character; The size of a byte is typically hardware dependent, but the modern de facto standard is 8 bits. However, byte has been used for numbers of bits other than 8. To avoid the risk of confusion ISO/IEC IEC 80000-13:2008 strongly recommends that the name byte and the symbol "B" (capital letter) be used only for 8-bit bytes. A computer with 8-bit bytes can distinguish 28 = 256 different characters. The symbol "B" is not international and should not be confused with the symbol "B" for bel

Prefixes for binary multiples
Computers use bits (binary digit), which are composed of ones and zeros. The decimal number system in contrast has ten unique digits, zero through nine. But although computer data and file size is normally measured using the binary number system (counted by factors of two 1, 2, 4, 8, 16, 32, 64, etc), the prefixes for the multiples were based on the metric/SI system because computer industry noticed that 210 was very nearly equal to 1000 and started using the SI prefix "kilo" to mean 1024! So, although a metric/SI "kilo" equals 1,000 (e.g. one kilogram = 1,000 grams), a binary "Kilo" equals 1,024 (e.g. one Kilobyte = 1,024 bytes). Not surprisingly leading to confusion, particularly when many storage device manufacturers and telecommunications engineers use the decimal prefixes. So a "500 GB hard drive" may show only 465 GB (500,000,000,000 bytes) on the computer. No Surprise, some may feel they have been cheated out of 35 GB. A big potential for confusion and for incompatibility in standards and in implemented systems exists.

In December 1998, the International Electrotechnical Commission (IEC) approved a new standard. Instead of using the metric prefixes for multiples in binary code, the new IEC standard called for specific prefixes for binary multiples made up of only the first two letters of the metric prefixes and adding the first two letters of the word "binary". Instead of Kilobyte (KB) or Gigabyte (GB), the new terms would be kibibyte (KiB) or gibibyte (GiB).


The common use of metric/SI prefixes for binary multiples can lead to confusion over whether value is binary or decimal. Use of "k" for decimal kilo and "K" for binary helps but not with other prefixes like mega (M) and giga (G). Symbol b for bit and B for byte is used to differentiate, but is still subject to confusion.

kb - kilobit - 1000 (103) bits
Kb - kilobit - 1024 (210) bits
kB - kilobyte - 1000 (103) bytes
KB - Kilobyte - 1024 (210) bytes
Mb - megabit - 1000000 (106) or 1048576 (220) bits
MB - megabyte - 1000000 (106) or 1048576 (220) bytes

New IEC standard should make things clearer. Confusion may still exist with use of old and new metric/SI prefixes.

KiB - kibibyte - 1024 (210) bytes
MB - megabyte - 1000000 (106) bytes. (SI prefix for decimal use only - may cause confusion with old system).

Symbol Prefix SI Binary Size difference
k kilo 103   = 10001 210 = 10241 2.40%
M mega 106   = 10002 220 = 10242 4.86%
G giga 109   = 10003 230 = 10243 7.37%
T tera 1012 = 10004 240 = 10244 9.95%
P peta 1015 = 10005 250 = 10245 12.59%
E exa 1018 = 10006 260 = 10246 15.29%
Z zetta 1021 = 10007 270 = 10247 18.67%
Y yotta 1024 = 10008 280 = 10248 20.89%

Symbol Prefix
Ki kibi, binary kilo kibibyte (KiB) 210 bytes 1024 B
Mi mebi, binary mega mebibyte (MiB) 220 bytes 1024 KiB
Gi gibi, binary giga gibibyte (GiB) 230 bytes 1024 MiB
Ti tebi, binary tera tebibyte (TiB) 240 bytes 1024 GiB
Pi pebi, binary peta pebibyte (PiB) 250 bytes 1024 TiB
Ei exbi, binary exa exbibyte (EiB) 260 bytes 1024 PiB
Zi zebi, binary zetta zebibyte (ZiB) 270 bytes 1024 EiB
Yi yobi, binary yotta yobibyte (EiB) 280 bytes 1024 ZiB

Data Transfer Rate - bits per second and bytes per second are confusing to those outside the specific industries. Terms such as 56K, 56 kb/s, 56Kb/s, 56 kbps, 56 Kbps, 56 kBps, 56 KBps etc. don't help. In most cases bitrate prefixes are used in the decimal sense.