A binary unit of information equal to 8 bits. Unfortunately, the storage of binary numbers in computers is not entirely standardized. Because computers store information in 8-bit bytes (where a bit is a single binary digit), depending on the "word size" of the machine, numbers requiring more than 8 bits must be stored in multiple bytes. The usual FORTRAN77 integer size is 4 bytes long. However, a number represented as (byte1 byte2 byte3 byte4) in a VAX would be read and interpreted as (byte4 byte3 byte2 byte1) on a Sun. The situation is even worse for floating-point (real) numbers, which are represented in binary as a mantissa and characteristic, and worse still for long (8-byte) reals!

The naming of large multiples of bytes follows standard SI prefixes, as summarized in the following table.

Unfortunately, there is some ambiguity in the meanings of the prefixes kilo-, mega-, etc., when applied to units of information. This arose historically out of the fact that 2^(10)=1024 approx 1000, so "kilobyte" was used to mean 1024 bytes, "megabyte" to mean 2^(20)=1048576 bytes, etc. However, such usage is now deprecated in favor of the usual SI unit prefixes, and a special set of prefixes have been invented for binary powers of information units, summarized in the table below.

See also

Baud, Bit, Crumb, Exbibyte, Gibibyte, Gigabyte, Kibibyte, Kilobyte, Mebibyte, Megabyte, Nibble, Pebibyte, Petabyte, Tebibyte, Terabyte

Explore with Wolfram|Alpha


Barrow, B. "A Lesson in Megabytes." IEEE Standards Bearer. p. 5, Jan. 1997.IEC 60027-2. Letter Symbols to Be Used in Electrical Technology--Part 2: Telecommunications and Electronics, 2nd ed. November 2000.National Institute of Standards. "Prefixes for Binary Multiples."

Referenced on Wolfram|Alpha


Cite this as:

Weisstein, Eric W. "Byte." From MathWorld--A Wolfram Web Resource.

Subject classifications