{
  "slug": "binary-prefix",
  "term": "Binary prefix",
  "aliases": [
    "IEC binary prefix",
    "Binary multiple prefix"
  ],
  "definition": "A binary prefix specifies an exact power-of-1024 multiple of an information unit, such as kibi (Ki), mebi (Mi) or gibi (Gi).",
  "note": "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. [iec-units] [nist-prefixes]\n\nComparison: 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. [hesela-capacity-units]",
  "status": "unknown",
  "advantages": [],
  "limitations": [
    {
      "text": "A unit label does not establish whether a value describes raw, usable, free or effective capacity.",
      "citationIds": [
        "hesela-capacity-units"
      ]
    }
  ],
  "related": [
    "raw-capacity",
    "usable-capacity",
    "effective-capacity",
    "throughput-storage"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "citations": [
    {
      "id": "iec-units",
      "title": "IEC style guide: Units and symbols, decimal and binary byte multiples",
      "url": "https://styleguide.iec.ch/?docs=iec/typographic/units-and-symbols",
      "accessed": "2026-10-23"
    },
    {
      "id": "nist-prefixes",
      "title": "NIST SP 330, Section 3: decimal and binary prefixes",
      "url": "https://www.nist.gov/pml/special-publication-330/sp-330-section-3",
      "accessed": "2026-10-23"
    },
    {
      "id": "hesela-capacity-units",
      "title": "Hesela: capacity units versus accounting deductions",
      "url": "https://hesela.com/analyses/sparse-files-preallocation-thin-capacity/#capacity-units",
      "accessed": "2026-10-23"
    }
  ],
  "updated": "2026-10-23",
  "provenance": [
    "Prefix factors follow IEC and NIST; the TB-to-GiB/TiB values are arithmetic conversions, not measured device capacities."
  ]
}