Unit Converter
Convert length, weight, temperature and volume units instantly with exact conversion factors — have your browser work out how many miles are in a kilometre, pounds in a kilogram or Fahrenheit in a Celsius reading. Fast, private and free.
What is a unit converter?
A unit converter is a tool that changes a measurement expressed in one unit into the equivalent value in another unit of the same kind — kilometres to miles, kilograms to pounds, or Celsius to Fahrenheit. Because the world still mixes metric and imperial systems, quick, accurate conversion saves time and prevents costly mistakes.
This free online unit converter covers four everyday categories: length, weight, temperature and volume. For most categories it multiplies by a fixed conversion factor — a metre is 100 centimetres, a pound is 0.45359237 kilograms — so the math is exact. Temperature is the exception, because Celsius, Fahrenheit and Kelvin start at different zero points, so the converter applies formulas like °F = °C × 9/5 + 32 instead of a simple multiplier. Everything runs in JavaScript in your browser, so results appear the moment you type and nothing is uploaded anywhere.
How to use
- Pick a category tab: Length, Weight, Temperature or Volume.
- Enter a value.
- Choose the unit you are converting from and the unit you want.
- The result appears instantly.
Example
To convert 10 kilometres to miles, choose the Length tab, type 10, set From to Kilometre and To to Mile — the result is about 6.21 miles. Switch to the Temperature tab and enter 100 with From Celsius and To Fahrenheit to get 212 °F. On the Weight tab, 5 kilograms becomes about 11.02 pounds, and on the Volume tab, 3 litres is roughly 0.79 US gallons.
Conversion factors
Length 1 mile = 1.609344 km 1 foot = 0.3048 m
1 inch = 2.54 cm 1 yard = 0.9144 m
Weight 1 pound = 0.45359237 kg 1 ounce = 28.3495 g
Volume 1 US gallon = 3.78541 L 1 cup = 236.588 mL
Temp °F = °C × 9/5 + 32 K = °C + 273.15
Who is this unit converter for?
This free unit converter is built for anyone who needs to make a conversion quickly, but a few groups reach for it most often.
- Students and young adults: Physics and maths homework runs on unit conversions. A unit converter for students switches between metric and imperial in seconds.
- Designers and developers: Builders of dashboards and maps need length, weight and volume logic; this free unit converter is a unit converter for developers.
- Professionals: Engineers, planners and tradespeople convert units daily, trusting the unit converter for km to miles, kg to lbs and more.
- Curious users: If you have ever asked how many miles are in a kilometre, the unit converter settles it instantly.
Common unit conversion table
These are the exact factors the converter uses, rounded to six decimals.
| Conversion | From | Equals |
|---|---|---|
| Kilometre to mile | 1 km | 0.621371 mi |
| Mile to kilometre | 1 mi | 1.609344 km |
| Kilogram to pound | 1 kg | 2.204623 lb |
| Pound to kilogram | 1 lb | 0.453592 kg |
| Litres to US gallons | 1 L | 0.264172 gal |
| Metre to feet | 1 m | 3.280840 ft |
| Inch to centimetre | 1 in | 2.54 cm |
Common use cases
- Travel and navigation: convert miles to kilometres, pounds to kilograms or Fahrenheit to Celsius when planning a trip or reading foreign signs.
- Cooking and baking: scale recipes that use cups and ounces into grams and millilitres, or the other way round.
- Study and work: rapidly convert units in maths, science and engineering homework and problems.
- Fitness and health: swap between metric and imperial weights, distances and temperatures for training goals.
Pro tips
- Temperature isn’t a multiplier: use °F = °C × 9/5 + 32 and K = °C + 273.15 — the tool handles this automatically.
- Flip direction with the dropdowns: keep your value and just change the To unit to reverse the conversion.
- Read scientific notation: very large or very small results appear in exponential form to stay readable.
- Stay exact: long standard factors such as 1 mile = 1.609344 km are used, so answers stay precise to many decimals.
FAQ
What is a unit converter?
A tool that changes a value from one unit to another in the same category, such as kilometres to miles or Celsius to Fahrenheit.
What units can I convert with this unit converter?
You can convert length (metres, kilometres, centimetres, millimetres, miles, yards, feet, inches), weight (kilograms, grams, milligrams, pounds, ounces), temperature (celsius, fahrenheit, kelvin) and volume (litres, millilitres, cubic metres, gallons, cups).
How many miles is a kilometre?
One kilometre is 0.621371 miles, so 5 km is roughly 3.1 miles. One mile is 1.609344 km.
How do I convert celsius to fahrenheit?
Use °F = °C × 9/5 + 32. So 100 °C = 212 °F and 0 °C = 32 °F.
How many kilograms are in a pound?
One pound is exactly 0.45359237 kg — so a pound is about 0.45 kg.
How many litres are in a US gallon?
One US gallon is 3.785411784 litres, so a gallon is a little under 4 litres.
Why can't I just multiply to convert temperature?
The Celsius, Fahrenheit and Kelvin scales have different zero points, so temperature needs an offset as well as a scale factor.
Are these conversions exact?
Yes — this converter uses exact, standard international factors for every unit.
Is this converter free and private?
Yes. It is free, runs entirely in your browser, and no data is uploaded.
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