About UnifyUnits

Who builds it

UnifyUnits is designed, built, and maintained by Satheez, a software engineer. The project started as a response to converter sites that bury a simple answer under clutter: the goal here is an instant, precise result on a page that loads fast and states where its numbers come from. The site is a single-developer project, which keeps it focused — every conversion page, definition, and factor passes through one set of hands and one review standard.

Questions, corrections, or suggestions are welcome via the contact page. Factual corrections are prioritized.

Where the numbers come from

Every conversion factor on UnifyUnits is sourced from international measurement standards, not copied from other converter sites:

• NIST Special Publication 811 — the U.S. national standard guide for SI usage and the authoritative table of conversion factors between SI and non-SI units.
• BIPM SI Brochure (9th edition) — the international definition of the SI base units, maintained by the International Bureau of Weights and Measures.

Exact legal definitions are used where they exist — for example, the international foot is exactly 0.3048 meters under the 1959 international yard and pound agreement, and the pound is exactly 0.45359237 kilograms. Unit definitions shown on converter pages cite these same standards.

How the conversion engine works

Conversions run on Decimal.js, an arbitrary-precision decimal arithmetic library, instead of native floating-point math. This avoids the rounding artifacts binary floating point introduces (the classic 0.1 + 0.2 ≠ 0.3 problem) in chained multiplications.

Most units convert through a multiplicative factor to a base unit per category — meters for length, kilograms for mass — so any pair converts in two exact steps. Units that cannot be expressed as a single factor, such as Celsius and Fahrenheit, use explicit formula-based definitions instead. Every factor and formula is covered by automated tests that run before each release.

Accuracy, independence, and corrections

Results are computed at full precision and then rounded for display, so the rounding you see never feeds back into the math. Where a factor is defined exactly by a standard, the exact value is stored; where a standard publishes a truncated value, the published value is used as-is rather than a re-derived approximation. Each converter page also shows the manual calculation steps, so any result can be checked by hand against the stated factor.

UnifyUnits has no sponsored content and no paid placement — nothing on a converter page is influenced by advertisers. If you find a factor, definition, or fact that disagrees with the cited standards, report it through the contact page; confirmed errors are corrected in the next deployment and noted against the source that defines the unit.