Unit Converter
Convert between length, weight, and temperature units
How to use this tool
- Pick a category: length, weight or temperature. The unit lists change to match.
- Type the value you want to convert. The result appears as you type, with nothing to submit.
- Choose the unit you are converting from and the unit you want.
- Use the swap button to reverse the direction without retyping the number.
About this tool
Convert between the units people actually need day to day, across three families: length, weight and temperature. Length runs from millimetres up to miles, which covers the two conversions that come up most: turning a metric measurement into feet and inches for someone who thinks in imperial, and turning a height or a room dimension the other way. Weight spans milligrams to metric tonnes and includes pounds and ounces, which is where recipes, shipping labels and gym equipment disagree with each other. Temperature covers Celsius, Fahrenheit and Kelvin. Temperature is handled separately in the arithmetic, and that is not an implementation detail. Length and weight scales share a zero point, so converting is one multiplication. Temperature scales do not: zero Celsius is 32 Fahrenheit, so each conversion needs an offset as well as a factor. A converter that treats them the same way is wrong, which is why every temperature value here routes through Celsius rather than through a single scale factor. The factors are the internationally agreed ones, several of which are exact by definition rather than measured: 2.54 centimetres to the inch, 0.45359237 kilograms to the pound, 1,609.344 metres to the mile. Everything is calculated in your browser, so the tool keeps working with no connection and nothing you type is sent anywhere.
Frequently asked questions
What units can I convert here?
Length covers metres, kilometres, centimetres, millimetres, miles, yards, feet and inches. Weight covers kilograms, grams, milligrams, pounds, ounces and metric tonnes. Temperature covers Celsius, Fahrenheit and Kelvin. Pick a category first and the unit lists change to match.
Why is temperature converted differently from length and weight?
Because length and weight scales share a zero point, so converting is a single multiplication. Temperature scales do not: zero Celsius is not zero Fahrenheit. Each conversion needs an offset as well as a factor, which is why 0 degrees Celsius is 32 Fahrenheit rather than 0.
How accurate are the conversions?
They use the standard internationally agreed factors, such as exactly 0.0254 metres to the inch and 0.45359237 kilograms to the pound. Results are rounded for display, so a value converted and converted back may differ in the last decimal place.
What is the difference between weight and mass?
Strictly, mass is how much matter something contains and weight is the force gravity exerts on it. Kilograms and pounds as used here are mass units. In everyday use on Earth the distinction does not change the number, which is why the two words are used interchangeably outside physics.
Is a US pound the same as a UK pound?
For mass, yes: both are the international avoirdupois pound of 0.45359237 kilograms. Volume is where they diverge, because a US gallon and pint are meaningfully smaller than the imperial ones, which is a frequent source of trouble in recipes.
Does the converter work offline?
The conversion arithmetic runs entirely in your browser with no network call, so once the page has loaded it keeps working without a connection. Nothing you enter is sent anywhere.