Megabyte (MB)
Definition
A megabyte (symbol MB) is a unit of digital information equal to exactly 1,000,000 bytes under the decimal definition standardized by IEC 80000-13. The closely related binary unit, the mebibyte (MiB), is 2²⁰ = 1,048,576 bytes; the two differ by about 4.86%.
History
Megabyte appeared in computing in the early 1970s for memory and storage capacities. Hardware vendors typically used the decimal definition (10⁶ B), while operating systems and memory modules used the binary definition (2²⁰ B). The mismatch produced the long-running disagreement between advertised and reported drive sizes.
IEC introduced binary prefixes in 1998 (kibi, mebi, gibi, etc.) to resolve the ambiguity; IEC 80000-13 (2008) made MB strictly decimal and MiB binary. The decimal definition is now used by storage manufacturers, network transfer rates, and most operating systems other than Windows.
Standard reference
Defined by IEC 80000-13 (2008) as exactly 1,000,000 bytes (10⁶ B). The binary mebibyte (MiB) of 1,048,576 bytes is a separate unit under the same standard.
Common conversions
| 1 MB | = 1,000,000 B |
|---|---|
| = 1,000 KB | |
| = 0.001 GB | |
| ≈ 0.953674 MiB (binary) |