1 megabyte can mean two slightly different things, depending on context:

  • In most storage and networking contexts (SI/decimal):
    1 MB = 1,000 KB.
  • In many operating systems and technical contexts (binary):
    1 MB = 1,024 KB.

Think of it this way: if a download page says “5 MB,” it usually means 5 × 1,000 KB, but a computer’s file system may calculate with 1,024 KB per MB instead, which is why sizes sometimes look a bit off.