A binary prefix is a prefix attached before a unit symbol to multiply it by a power of 2. In computing, such a prefix is seen in combination with a unit of information (bit, byte, etc.), to indicate a power of 1024.

The computer industry has historically used the units kilobyte, megabyte, and gigabyte, and the corresponding symbols KB, MB, and GB, in at least two slightly different measurement systems. In citations of main memory (RAM) capacity, gigabyte customarily means 7009107374182400000♠1073741824 bytes. As this is the third power of 1024, and 1024 is a power of two (2), this usage is referred to as a binary prefix.