Unit Converter

Unit Converter — Complete Guide

How the converter works

The Unit Converter handles six measurement categories — length, weight, temperature, area, volume and speed — in a single interface. Choose a category, set the From and To units, type a value, and the result appears instantly, together with a small panel of related conversions so you can compare several units at once. The swap button exchanges the two units without retyping the number.

For every category except temperature, conversion is a matter of scaling: each unit is stored as a factor that expresses it in one shared base unit, and the tool multiplies by the source factor and divides by the target factor. Temperature is the exception and is handled with dedicated formulas, because its scales have different zero points instead of a common origin.

Common conversion factors

The table below lists the definitions the converter relies on. Length, weight, area, volume and speed all use exact international definitions, so these are fixed constants rather than rounded approximations.

Temperature is not a simple ratio

Temperature uses formulas rather than factors:

That is why 0 °C is 32 °F rather than 0 °F, and why a doubling of a Celsius value does not double the Fahrenheit value. The converter therefore routes temperature through a separate code path, converting first to Celsius as the base and then out to the target scale.

Precision, rounding and unit systems

Results are formatted adaptively: values of 100 or more show two decimals, values from 1 to 100 show up to four, and very small values keep more digits so that tiny numbers do not collapse to zero. This is display rounding only — the underlying arithmetic keeps full precision.

Watch the US-versus-imperial distinction. A US gallon is 3.7854 L while an imperial gallon is 4.546 L, and the same split applies to pints, quarts and fluid ounces. If the wrong system is assumed, cooking and fuel figures can differ by about 20%. Always confirm which gallon, pint or ton a recipe or specification means.

A worked example

Convert 10 miles to kilometres. One mile equals 1.609344 km, so 10 miles = 16.09344 km, displayed as 16.09. In the same category, 10 miles is also 16,093.44 m and 17,600 yd. For weight, 150 lb × 0.45359237 = 68.0389 kg; for volume, 2 US gallons × 3.785411784 = 7.5708 L. Each of these appears live in the related-conversions panel as soon as you pick a category and a starting unit.