About FractionReference

FractionReference is a permanent reference for moving between exact numbers and practical measurements: fractions, decimals, percentages, and the fractional inches a rule actually has marks for.

It is built to answer a fourth-grader and a machinist with the same page. The simple layer — what is 3/8 as a decimal — leads every page, stated big and plainly. The practical layer — what is the simplest fraction within half a millimetre of 10 mm — sits underneath, with its errors stated and its ranking documented. The site never chooses between those audiences, because the range is the point.

Every number is exact rational arithmetic from the values entered, computed by the same deterministic code at build time and in the browser, and checked by a test suite on every build. Where a value is rounded for display, the page says so. The full account is on the methodology page.

FractionReference is part of a small family of reference sites: BenchReference for workshop standards — drills, threads, fasteners — RoadReference for vehicle fitment, and ColorTable for exact digital color. They share a design, an engraved hand, and a habit: answer first, data over prose, printable, no accounts, no popups.

Found something wrong? A wrong number here would matter; the site would rather know. Every calculation is reproducible from the page that shows it, so a counterexample is easy to state.