Unit Converter

How do you convert a measurement into another unit?

Choose a category, select the source in From and the target in To, then enter a number in Value. For example, select Length, Foot (ft), and Meter (m), then enter 90: the result is 27.432 m with Auto precision. The calculation is 90 × 0.3048 = 27.432. There is no separate conversion button; results update from your current entries.

The All units table converts the same input into every unit in the selected category. Select a row to make that unit the target without retyping the input. These examples use the stored conversion factors and Auto precision for the main result.

Which compound measurements can you enter?

The Value field accepts four ordered pairs: ft/in, st/lb, h/min, and lb/oz. Examples include 5 ft 8 in, 10 st 4 lb, 1 h 30 min, and 2 lb 3 oz. Choose the matching category first: Length, Weight, or Time. The parser adds the two measurements through that category's base unit rather than treating the text as a decimal number.

Both parts need a number and unit. Enter 10 st 4 lb, rather than 10 stone 4. Reversing the order or mixing categories produces an error. Feet and inches also accept quote notation such as 5'8". A leading minus sign applies to the whole compound measurement. For an ordinary scalar, enter only the number and use From to specify its unit.

Some targets also show a Rounded compound line. It rounds to whole minor units, so it is an everyday measurement summary rather than an additional precise result. For example, 71.9 inches is summarized as 6 ft 0 in. Read the main decimal result when the fractional part matters.

How do precision, copying, and unit search work?

Result precision offers Auto precision and 2, 4, 6, or 10 significant digits. Significant digits count meaningful digits across the number, rather than fixing a number of decimal places. With two significant digits, 27.432 becomes 27; with four it becomes 27.43. Auto uses up to eight significant digits for ordinary main results and six for the comparison table. Very large or small nonzero main results use scientific notation.

The Copy converted value control copies the formatted main result with its target symbol. Increasing display precision does not improve a rounded conversion factor: the tool stores 0.453592 kilograms per pound, for example. Calculations run in the browser using the local unit definitions. The converter does not request a remote conversion result.

Use Find a unit across categories to search labels, symbols, or aliases such as feet or mph. Selecting a match chooses its category and source unit and clears the input. Star a result to keep it among session favorites; those favorites live in component state. Swap from and to units exchanges the two selections while retaining your entered value.

Why do temperature and fuel economy need different formulas?

Most categories multiply into a base unit and divide out to the target. Temperature includes offsets: °F = °C × 9/5 + 32, and K = °C + 273.15. Thus 20°C converts to 68°F, while 40°C converts to 104°F. Doubling the Celsius value does not double the Fahrenheit result. The Conversion formula panel shows the relationship for one source unit, not a complete equation for arbitrary inputs.

Fuel economy uses L/100 km as its base. The stored US factor gives L/100 km = 235.214583 ÷ mpg US, so 30 mpg US displays as 7.8404861 L/100 km in Auto precision. The UK factor is 282.480936 instead. A larger mpg value produces a smaller consumption value. Reciprocal conversion from zero has no finite result and displays a dash.

Which unit definitions should you check before comparing results?

Volume separates US and UK gallons: the stored values are 3.78541 L and 4.54609 L respectively. Cooking measures use US definitions, including 0.2365882365 L per cup. Area uses its own factors, including 1,000,000 m² per km² and 4,046.86 m² per acre. Select Area for square measurements; converting a length does not calculate an area or volume.

Data size separates decimal kB, MB, GB, and TB from binary KiB, MiB, GiB, and TiB. One GiB is 1.073741824 GB before rounding. Pressure includes Pa, kPa, bar, psi, atm, and mmHg; energy includes J, kJ, cal, kcal, Wh, kWh, and BTU. Weight converts mass units through kilograms without a gravity adjustment. Use BMI Calculator if you need to combine body mass with height.

Time includes fixed average months of 30.436875 days and years of 365.2425 days. These represent durations, not specific calendar intervals. Use Date Difference Calculator for two calendar dates or Age Calculator for a birth date. The converter's eleven categories have separate unit lists; it does not convert between different physical quantities.