A unit of measurement equal to one million bits, used to specify the transmission speed of computer networks: Mb per second (Mb/s). Not to be confused with a Megabyte (MB), one million bytes, each consisting of 8 bits. A Megabyte is eight times larger than a MegabitMegabit A unit of measurement equal to one million bits, used to specify the transmission speed of computer networks: Mb per second (Mb/s). Not to be confused with a Megabyte (MB), one million bytes, each consisting of 8 bits. A Megabyte is eight times larger than a Megabit. It takes 8 seconds to transmit 1 Megabyte at a speed of 1 Megabit.. It takes 8 seconds to transmit 1 Megabyte at a speed of 1 Megabit.