A megabyte is a unit of information or computer storage equal to either 106 (1,000,000) bytes or 220 (1,048,576) bytes, depending on context. In rare cases, it is used to mean 1000×1024 (1,024,000) bytes.[citation needed] It is commonly abbreviated as Mbyte or MB (compare Mb, for the megabit). The term megabyte was coined in 1970.[1]
The term "megabyte" is ambiguous because it is commonly used to mean either 10002 bytes or 10242 bytes. The confusion originated as compromise technical jargon for the byte multiples that needed to be expressed by the powers of 2 but lacked a convenient name. As 1024 (210) is roughly equal to 1000 (103), roughly corresponding SI multiples began to be used as approximate binary multiples. By the end of 2007, standards and government authorities including IEC, IEEE, EU, and NIST, had addressed this ambiguity by promulgating standards requiring the use of megabyte to describe strictly 10002 bytes and "mebibyte" to describe 10242 bytes. This is reflected in an increasing number of software projects, but most file managers still show file sizes in "megabytes" ("MB") in the binary sense (10242 bytes). The term remains ambiguous and it can follow any one of the following common definitions:
1,000,000 bytes (10002, 106): This is the definition recommended by the International System of Units (SI) and the International Electrotechnical Commission IEC. This definition is used in networking contexts and most storage media, particularly hard drives, Flash-based storage, and DVDs, and is also consistent with the other uses of the SI prefix in computing, such as CPU clock speeds or measures of performance.
1,048,576 bytes (10242, 220): This definition is most commonly used in reference to computer memory, but most software that display file size or drive capacity, including file managers also use this definition. See Consumer confusion (in the "gigabyte" article).
1,024,000 bytes (1000×1024): This is used to describe the formatted capacity of USB flash drives[citation needed] and the "1.44 MB" 3.5 inch HD floppy disk, which actually has a capacity of 1,474,560 bytes.
Megabyte examples
1.44 MB floppy disks can store 1,474,560 bytes of data. MB in this context means 1,000×1,024 bytes.
Depending on compression methods and file format, a megabyte of data can roughly be:
