binary-prefix · unknown · also IEC binary prefix, Binary multiple prefix

Binary prefix

A binary prefix specifies an exact power-of-1024 multiple of an information unit, such as kibi (Ki), mebi (Mi) or gibi (Gi).

Related Observatory article: Binary prefix on hesela.com

Units: Binary prefixes distinguish powers of two from SI decimal prefixes. One GiB is 1,073,741,824 bytes; one GB is 1,000,000,000 bytes. One TiB is 1,099,511,627,776 bytes; one TB is 1,000,000,000,000 bytes. The prefixes multiply the named unit, so bits, bytes and bytes per second still describe different quantities. [1] [2]

Comparison: Dividing the same byte count by these factors gives exactly 1 TB as approximately 931.323 GiB or 0.909495 TiB. This is a unit conversion, not missing space. Parity, metadata and reservations are separate accounting deductions; state both the unit and the capacity layer. The worked example and executable conversion checks are linked below. [3]

Relations

related

Raw capacity, Usable capacity, Effective capacity, Storage throughput

Limitations

• A unit label does not establish whether a value describes raw, usable, free or effective capacity. [3]

Citations

1. IEC style guide: Units and symbols, decimal and binary byte multiples (accessed 2026-10-23)
2. NIST SP 330, Section 3: decimal and binary prefixes (accessed 2026-10-23)
3. Hesela: capacity units versus accounting deductions (accessed 2026-10-23)

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