The megabyte is a multiple of the unit byte for digital information. Its recommended unit symbol is MB, but sometimes MByte is used. The unit prefix mega is a multiplier of 1000000 (10⁶) in the International System of Units(SI).^[1] Therefore one megabyte is one million bytes of information. This definition has been incorporated into theInternational System of Quantities.

However, in the computer and information technology fields, several other definitions are used that arose for historical reasons of convenience. A common usage has been to designate one megabyte as 1048576bytes(2²⁰), a measurement that conveniently expresses the binary multiples inherent in digital computer memory architectures. However, most standards bodies have deprecated this usage in favor of a set of binary prefixes,^[2] in which this measurement is designated by the unit mebibyte (MiB). Less common is a measurement that used the megabyte to mean 1000×1024 (1024000) bytes.^[2]