Length Unit Converter

The metric system scales by powers of 10 through a fixed set of SI prefixes: milli- (÷1,000), centi- (÷100), kilo- (×1,000) — so 1 m = 100 cm = 1,000 mm, and 1 km = 1,000 m, with no other arithmetic to remember. The imperial system instead uses inherited, uneven ratios: 12 inches per foot, 3 feet per yard, 1,760 yards per mile. The two systems meet at exactly one bridge point: 1 inch = 2.54 cm, defined precisely, not measured.

The 2.54 cm figure is not a rounded approximation — it was fixed by international agreement in 1959, when the US, UK and other English-speaking countries formally agreed to define the international yard as exactly 0.9144 meters, which makes the inch (a 36th of a yard) exactly 2.54 cm by construction. Every other length conversion on this page — feet, yards, miles — descends from that single defined ratio, so this converter's outputs are exact rather than statistically rounded. It is the same agreement that fixed the pound at exactly 0.45359237 kg, the basis for every mass conversion elsewhere on this site.

A conversion factor for length does not carry straight over once a measurement is squared or cubed. Converting an area means squaring the length factor — 1 square meter is about 3.2808² ≈ 10.76 square feet, not 3.28. Converting a volume means cubing it — 1 cubic meter is about 3.2808³ ≈ 35.31 cubic feet, not 3.28 or even 10.76. This length converter is the right tool for a single dimension — a height, a distance, a width — but reapplying its factor directly to an area or volume figure is a common and easy mistake.

The exact conversion for meters to feet is 1 ÷ 0.3048 = 3.280839895..., an infinite non-repeating decimal despite the exact starting definition, because dividing by 0.3048 does not resolve cleanly. For construction, recipes or everyday use, four significant figures (3.281) is more than enough; for survey-grade or scientific work, keep more digits. The table above computes with full floating-point precision regardless of how the result is displayed, so rounding for readability never compounds into the next conversion — converting meters to feet and back again returns the original number, not a value drifted by accumulated rounding. There is one US-specific wrinkle worth knowing: a small set of state survey records still use the older US survey foot, defined by a slightly different historical ratio than the international foot this calculator uses. The two differ by about two parts per million — meaningless for everyday use, but occasionally relevant on old land surveys, which is why surveyors specify which foot a document uses.

Choose a unit to convert from, a unit to convert to, and enter the value. The result shows above, and the table lists the value in every unit at once — a fast way to sanity-check a number against a unit you're more familiar with, or to read off several equivalents without re-entering the value each time.