Megabit (Mb) is a data measurement unit applied to digital computer or media storage. One Mb equals one million (1,000,000 or 106) bits or 1,000 kilobits (Kb).
The International System of Units (SI) defines the mega prefix as a 106 multiplier or one million (1,000,000) bits. The binary mega prefix is 1,048,576 bits or 1,024 Kb. The SI and binary differential is approximately 4.86 percent.
Techopedia explains Megabit (Mb)
Central processing units (CPU) are built with data control instructions for bits--the smallest data measurement unit. Bits are magnetized and polarized binary digits that represent stored digital data in random access memory (RAM) or read-only memory (ROM). A bit is measured in seconds and characterized by high-voltage 0 (on) or 1 (off) values.
Mb continue to apply to a number of measurement contexts, including:
Internet/Ethernet data: Download and data transfer rate (DTR) speeds as megabits per second (Mbps).
Data storage: 16-bit game cartridges with eight-Mb storage, including Mega Drive (Genesis) and Super Nintendo Entertainment System (SNES).
Random-access memory (RAM) and read only memory (ROM): For example, a double-data-rate three (DDR3) chip contains 512Mb.
Web files transfer as megabytes (MB). For example, a network connection with an eight Mbps DTR must reach a Web DTR of one megabyte (MB) per second (MBps).
In 2000, the Institute of Electrical and Electronics Engineers (IEEE) incorporated the International Electrotechnical Commission (IEC) formal approval of SI metric prefixes (for example, MB as one million bytes and KB as one thousand bytes). Newly added metric terms include:
Kibibyte (KiB) equals 1,024 bytes.
Mebibyte (MiB) equals 1,048,576 bytes.
Gibibyte (GiB) equals 1,073,741,824 bytes.