mebibyte

A mebibyte (MiB) is a unit of digital information storage equal to 2⁲⁰ bytes, or 1,048,576 bytes. It is part of the binary prefix system introduced by the International Electrotechnical Commission (IEC) in 1998 to provide a clear distinction from the decimal-based metric prefixes used for larger quantities such as megabyte (MB), which denotes one million (10⁶) bytes. The term combines the prefix “mebi‑” (derived from “mega‑binary”) with “byte”.

Binary prefixes were created to resolve confusion in computing contexts where powers of two predominate. Historically, many operating systems and hardware specifications used the term megabyte to refer to 2²⁰ bytes, while manufacturers of storage media used the decimal definition. This discrepancy led to differences in reported capacities, prompting the IEC to standardize terms like kibibyte (KiB), mebibyte (MiB), gibibyte (GiB), and so on.

In practice, the mebibyte is used in fields that require precise binary measurements, such as computer memory specifications, file system limits, and software development documentation. Operating systems and programming languages often expose sizes in mebibytes when reporting memory usage or disk quotas, especially in Unix‑like environments where the “du” and “ls” commands can display values with the “-h” option indicating binary multiples.

While the adoption of binary prefixes has grown, the megabyte remains more familiar to the general public. Nevertheless, technical literature and standards continue to prefer the mebibyte for accuracy, ensuring that a MiB always represents exactly 1,048,576 bytes.