isr.co.ro : glossary Megabyte (MB) Literally, a million (1,000,000) bytes. In most computer contexts, each thousand is replaced by a binary thousand equal to 1024, which is 2 to the 10th power. So a megabyte is taken as 1024 x 1024, or 1,048,576 bytes. However, many disk-driver makers have recently taken to using the smaller decimal megabyte so they can claim a larger drive-size number. For example, a disk drive that had been specified as 850 megabytes using the binary megabyte suddenly jumps in size to 891 megabytes using the smaller megabyte value.