Megabyte

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This article is about a unit of data. For the ReBoot character, see Megabyte (ReBoot).

v • d • e Quantities of bytes
SI prefixes		Historical use		Binary prefixes
Symbol (name)	Value	Symbol	Value	Symbol (name)	Value
kB (kilobyte)	1000¹ = 10³	KB	1024¹ = 2¹⁰	KiB (kibibyte)	2¹⁰
MB (megabyte)	1000² = 10⁶	MB	1024² = 2²⁰	MiB (mebibyte)	2²⁰
GB (gigabyte)	1000³ = 10⁹	GB	1024³ = 2³⁰	GiB (gibibyte)	2³⁰
TB (terabyte)	1000⁴ = 10¹²	TB	1024⁴ = 2⁴⁰	TiB (tebibyte)	2⁴⁰
PB (petabyte)	1000⁵ = 10¹⁵	PB	1024⁵ = 2⁵⁰	PiB (pebibyte)	2⁵⁰
EB (exabyte)	1000⁶ = 10¹⁸	EB	1024⁶ = 2⁶⁰	EiB (exbibyte)	2⁶⁰
ZB (zettabyte)	1000⁷ = 10²¹	ZB	1024⁷ = 2⁷⁰	ZiB (zebibyte)	2⁷⁰
YB (yottabyte)	1000⁸ = 10²⁴	YB	1024⁸ = 2⁸⁰	YiB (yobibyte)	2⁸⁰

Legacy Units
Unit	Value
KB	2¹⁰ Bytes = 1024 Bytes
MB	2²⁰ Bytes = 1024 KB
GB	2³⁰ Bytes = 1024 MB
TB	2⁴⁰ Bytes = 1024 GB

A megabyte or Mbyte 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. It is commonly abbreviated as Mbyte or MB (not to be confused with Mb, which is used for the megabit). The term megabyte was coined in 1970.^[1]

1 Definition
2 Megabyte examples
3 See also
4 External links
5 References

[edit] Definition

The term "megabyte" is considered ambiguous by some 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 convenient naming. As 1024 (2¹º) is roughly equal to 1000 (10³), roughly corresponding SI multiples began to be used as approximate binary multiples. In the past few years, standards and government authorities including IEC, IEEE, EU, and NIST, have addressed this ambiguity by promoting the use of megabyte to describe strictly 1000² bytes and "mebibyte" to describe 1024² bytes. This shift is reflected in an increasing number of software projects, but most file managers still show file sizes as "megabytes" ("MB").

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 SI and 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 and the "1.44 MB" 3.5 inch HD floppy disk, which actually has a 1440 KiB capacity, that is, 1,440×1,024 bytes, or 1,474,560 bytes.