Physical unit converter

The definition matters as much as the number.

Length uses international inches, feet, yards and miles. One inch is exactly 0.0254 meters; one foot is 12 inches. Mass uses avoirdupois pounds and ounces: one pound is exactly 0.45359237 kilograms and one ounce is 1/16 pound. These are mass units, not forces.

Volume uses liters and U.S. liquid gallons, quarts, pints and fluid ounces. One U.S. gallon is 231 cubic inches, exactly 3.785411784 liters; it contains 4 liquid quarts, 8 liquid pints or 128 U.S. fluid ounces. Imperial and U.S. dry measures are different and are not included. Mass cannot be converted into volume without material density.

Area uses metric units, square international feet/inches and hectares. A square foot is (0.3048)^2 square meters; a hectare is 10,000 square meters. Land-survey units and acres are not included.

For absolute temperature, °C = K − 273.15 and °F = K × 9/5 − 459.67. For example, 32 °F is 0 °C and 273.15 K. Offsets do not apply to temperature differences; this tool does not calculate those. Values below absolute zero are rejected.

Calculations use exact rational factors internally. The main decimal result is an approximation rounded to 12 significant digits; the report also contains an exact fraction. This does not add precision to the original measurement. Sources: NIST conversion factors and NIST temperature relationships. No live data or API is used.