From Wikipedia, the free encyclopedia

A megabit is a unit of information or computer storage, abbreviated Mbit (or Mb).

1 megabit = 10⁶ = 1,000,000 bits which is equal to 125,000 bytes or 125 kilobytes.

The megabit is most commonly used when referring to data transfer rates in network speeds, e.g. a 100 Mbit/s (megabit per second) Fast Ethernet connection. In this context, like elsewhere in telecommunications, it always equals 10⁶ bits. Residential high speed internet access is often advertised incorrectly in megabits (a unit of information) rather than megabit per second.

A binary counterpart of the megabit, useful for measuring RAM and ROM chip capacity, is the mebibit. However, it is not universally accepted and as such some ambiguity exists in the usage of the term "megabit". Before the ratification of the term "mebibit" as part of IEC 60027, manufacturers had already chosen to use the term megabit to refer to the binary quantity 1024² bits, even though the megabit had already been established as a decimal unit in terms of data transfer rates. The practice of using megabit or Mbit in this context is still widespread in the RAM and ROM manufacturing industry in 2007 despite the availability of an unambiguous alternative.

In the 16-bit games console era, the 'megabit' became a commonly-used measure of the size (computer data storage capacity) of games cartridges. This "megabit" actually equals one mebibit (Mibit). The vast majority of SNES and Sega Mega Drive (Genesis) games were produced on standard 8 megabit cartridges, although 4 megabit cartridges were not uncommon and, later in the life of these consoles, graphically-intensive titles would appear on 12, 16, even 32 megabit cartridges. Tales of Phantasia and Star Ocean were 48 megabit.

The rule is: 8 bits = 1 byte. Therefore a 4 megabit cartridge had a capacity of 512 KiB, an 8 megabit cartridge held 1 MiB of data, and so on.

• megabyte
• binary prefix
• orders of magnitude (data)