How many bytes are in a megabyte?

There are three definitions of megabyte (MB), two of which are commonly used in computing:

  • 1000 × 1000 = 1,000,000 bytes in a megabyte - This is the standard SI definition, used for most media measurements (like hard drives and DVDs), for networking, and in some software (like Mac OS X and Linux).
  • 1024 × 1024 = 1,048,576 bytes in a megabyte - This is the definition commonly used by memory manufacturers and in some software (like Microsoft Windows). The official term for this unit is "mebibyte" (MiB).
  • 1024 × 1000 = 1,024,000 bytes in a megabyte - This definition was used in the once-common "1.44 MB" floppy disk, and is usually considered a mistake