Both Mbps and MBps are measures of data used in computer systems. Mbps stands for megabits per second, and MBps stands for megabytes per second. Since a single byte is composed of eight bits, a megabyte is composed of eight megabits or eight million bits. While data transfer rates are typically measured in bits, things like the size of a hard drive or the amount of random access memory installed in a computer are usually measured in bytes.