About AllUnits

Who runs this site

AllUnits is maintained by its editorial desk, which is responsible for the conversion factors, tables and corrections on the site. If a value looks wrong, email [email protected] with the page address and the number you expected.

How conversions are calculated

Each converter uses a fixed factor or formula rather than a rounded lookup table. For example, one international mile is exactly 1,609.344 metres, so kilometres are converted with mi x 1.609344. Temperature pages use the offset formula. On-page results are rounded to the number of decimals stated on the page; the calculation itself keeps full precision.

The calculator works in both directions: type into either field and the other updates immediately. Conversion tables are generated from the same factor, so the table and the calculator cannot disagree.

Standards and sources

• NIST Special Publication 811, Guide for the Use of the International System of Units (SI).
• BIPM SI Brochure, 9th edition (2019), the definitions of the SI base units.
• IEC 80000-13:2008, Quantities and units - Part 13: Information science and technology, which defines the binary prefixes used for KiB, MiB and GiB.
• The 1959 international yard and pound agreement: 1 yard = 0.9144 m and 1 pound = 0.45359237 kg exactly. These definitions give 1 mile = 1,609.344 m and 1 inch = 25.4 mm.
• US gallon = 231 cubic inches = 3.785411784 L; imperial gallon = 4.54609 L. The two are not interchangeable in recipes or fuel figures.

Updates

• 2026-11-09: Removed the Arabic and Hindi editions, rewrote the FAQ sections so each page answers its own conversion, and added a Guides and Reference Tables section to the homepage.
• 2026-11-08: Site launched with 30 converters in 10 languages.