MiB

MiB stands for mebibyte, a unit of digital information equal to 1,048,576 bytes (2^20). It is part of the IEC binary prefix system introduced to distinguish binary-based sizes from decimal prefixes. The mebibyte uses the prefix mebi- with the byte unit, forming MiB, and fits alongside KiB (2^10 bytes) and GiB (2^30 bytes) in the series of binary multiples.

These prefixes were standardized to reduce confusion between powers of two and powers of ten. In particular, the IEC 80000 series defines the binary prefixes KiB, MiB, GiB, and so on, defining their exact byte counts, whereas the traditional megabyte (MB) has often been used in decimal form as 1,000,000 bytes. As a result, MiB is commonly used in technical contexts such as memory sizes and certain file sizes, where precise binary multiples are important.

In practice, MiB is used to express amounts of computer memory (RAM, cache) and data transfer sizes. For example, a 500 MB (decimal) file is about 476.84 MiB, and a system with 8 GiB of RAM contains 8,589,934,592 bytes, which equals 8192 MiB. Awareness of the distinction between MB and MiB helps avoid misinterpretation of storage and memory specifications.

See also: byte, kilobyte (KB), megabyte (MB), gibibyte (GiB), kibibyte (KiB).