Unit Converter
Convert length, weight, temperature, volume, area, speed, pressure, energy, and other measurements across metric, US customary, and imperial units. Type in either direction and see the result immediately.
How to use the Unit Converter
Choose a measurement category, search for the source and target units, then enter a value in either box. The result updates immediately in both directions, so the field you edit becomes the source of the conversion.
Use the ⇄ swap button to flip the from/to units, or click Copy bookmarkable link to share an exact conversion. Precision and notation controls, useful equivalents, and private browser history are available beside the result. You can also enter fractions such as 3 1/2, feet and inches such as 5 ft 8 in, or compatible expressions such as 2 km + 350 m.
Open Build a conversion table to create a range using the active unit pair. Set the start, end, and step values, then copy the table or download it as a CSV file for a spreadsheet.
Metric, imperial, and scientific conversions
The converter covers 15 categories for everyday tasks, travel, cooking, construction, engineering, computing, and science:
- Length and area: millimetres, centimetres, metres, kilometres, inches, feet, yards, miles, acres, and hectares.
- Weight and density: milligrams, grams, kilograms, ounces, pounds, stones, tonnes, and common density units.
- Temperature and volume: Celsius, Fahrenheit, Kelvin, litres, millilitres, cups, fluid ounces, pints, quarts, and gallons.
- Speed and fuel economy: kilometres per hour, miles per hour, metres per second, knots, MPG, and litres per 100 kilometres.
- Technical units: pressure, energy, power, torque, angles, time, and digital data storage.
US and imperial volume units are labeled separately where their definitions differ. Fuel economy conversions also account for the reciprocal relationship between MPG and L/100 km.
How conversion works
Each category uses a base unit. Every other unit is defined by a fixed ratio to that base. The converter multiplies your input by the source unit's ratio to get the base value, then divides by the target unit's ratio to produce the answer.
Temperature is the exception — because Celsius, Fahrenheit, and Kelvin have different
zero points, conversions use offset formulas rather than simple ratios. For example,
Fahrenheit to Celsius is (F − 32) × 5/9.
Common conversions at a glance
- 1 inch = 2.54 cm
- 1 mile = 1.60934 km
- 1 pound = 0.453592 kg
- 1 litre = 0.264172 gallons (US)
- 1 acre = 43,560 square feet
- 1 kilowatt = 1,000 watts
- Water freezes at 0°C / 32°F / 273.15 K
Frequently Asked Questions
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Does this converter support both metric and imperial units?
Yes. It handles the metric system (metres, kilograms, litres) and the imperial / US customary system (feet, pounds, gallons) across length, weight, temperature, volume, and speed — handy for travel, cooking, engineering, and international trade.
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Why is temperature conversion different?
Celsius, Fahrenheit, and Kelvin have different zero points, so conversions use offset formulas rather than simple multiplication. Water freezing at 0°C is 32°F and 273.15 K — same temperature, three different numbers.
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Can I type into either box?
Yes. The From and To fields both accept input and update each other live. Whichever field you last typed in becomes the source of the conversion.
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How precise are the results?
Choose automatic formatting or 2–12 significant digits, then select decimal, scientific, or engineering notation. The unrounded numeric result is also available to copy. Defined conversion constants retain their full internal precision.
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What are smart equivalents?
Smart equivalents show the same measurement in other useful units, prioritizing readable values and a mix of measurement systems rather than listing every possible unit.
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Does clearing history remove favorites?
No. Clear history removes saved conversion results only. Favorite and recent unit pairs remain available as shortcuts.
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Can I share a specific conversion?
Yes — click Copy bookmarkable link to create a URL containing the current category, units, and value so someone else can open the same view.
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Is my data private?
Yes — all conversions run entirely in your browser using JavaScript. Nothing you type is transmitted to any server. See our Privacy Policy for details.
