Units Verse defines its conversions against internationally recognised standards. The primary references below govern the definitions we use; where a unit is defined by national custom (for example, US survey vs. international measures) we use the modern international definition unless a variant is explicitly named.
Primary standards bodies
- BIPM — Bureau International des Poids et Mesures. Custodian of the SI and the SI Brochure, which defines the seven base units and the derived units used throughout the platform.SI Brochure.
- NIST — U.S. National Institute of Standards and Technology. Special Publication 811, "Guide for the Use of the International System of Units (SI)," and the NIST reference on constants, units, and uncertainty.NIST SP 811.
- ISO/IEC 80000 — "Quantities and units," the international standard for quantities, unit names, and symbols.
- IEC 60027 / IEC 80000-13 — binary prefixes (kibibyte, mebibyte, …) used by the data-storage converter.
Selected definitional constants
These exact definitions anchor the most common conversions on the site:
| Quantity | Exact definition |
|---|---|
| Inch | 1 in = 0.0254 m (exact) |
| Foot | 1 ft = 0.3048 m (exact) |
| Mile | 1 mi = 1609.344 m (exact) |
| Pound (avoirdupois) | 1 lb = 0.45359237 kg (exact) |
| US gallon | 1 gal = 3.785411784 L (exact) |
| Calorie (thermochemical) | 1 cal = 4.184 J (exact) |
| Temperature | °F = °C × 9/5 + 32; K = °C + 273.15 |
For a full explanation of how these definitions are applied, see ourconversion methodology. External links are provided for reference and are not affiliated with Units Verse.