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Bytes: SI Units vs IEC Units

Created on April 23, 2025 Updated on April 24, 2025

ComputerScience

MB is based on powers of 10 (1’000’000 Bytes), MiB is based on powers of 2 (1024**2).

I learned only recently that there are megabytes and mebibytes.

The International System of Units (“SI”) base their units in decimal, or powers of 10.

kB 	kilobyte	1'000 bytes
MB	megabyte	1'000'000 bytes (1000**2)
GB	gigabyte	1'000'000'000 bytes (1000**3)
TB	terabyte	1'000'000'000'000 bytes (1000**4)

On the other hand, the International Electrotechnical Commission (“IEC”) define bytes in binary, in powers of 2.

KiB	kibibyte	1'024 bytes
MiB	mebibyte	1'048'576 bytes (1024**2)
GiB	gibibyte	1'073'741'824 bytes (1024**3)
TiB	tebibyte	1'099'511'627'776 bytes (1024**4)