Length Converter
Convert between millimetres, centimetres, metres, kilometres, inches, feet, yards, miles and nautical miles.
Unit & Measurement Converters
Convert length, weight, volume, temperature, speed and more. Instant, exact and free.
All converters
Every category has a converter for any pair of its units. The conversions people ask for most have a page of their own, with the formula, a table and worked examples.
Weight and Mass Converter
Convert between milligrams, grams, kilograms, tonnes, ounces, pounds, stones and US or imperial tons.
Volume Converter
Convert between millilitres, litres and the US and imperial fluid ounces, cups, pints, quarts and gallons.
Temperature Converter
Convert between degrees Celsius, degrees Fahrenheit and kelvins.
Area Converter
Convert between square metres, square feet, acres, hectares and other units of area.
Speed Converter
Convert between metres per second, kilometres per hour, miles per hour, feet per second and knots.
Time Converter
Convert between milliseconds, seconds, minutes, hours, days and weeks, and average months and years.
Data Storage Converter
Convert between bits, bytes and the decimal (kB, MB, GB, TB) and binary (KiB, MiB, GiB, TiB) units.
Pressure Converter
Convert between pascals, kilopascals, bars, atmospheres, PSI and millimetres of mercury.
Energy Converter
Convert between joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours and BTU.
Power Converter
Convert between watts, kilowatts, horsepower and metric horsepower (PS).
Force Converter
Convert between newtons, kilonewtons and pounds-force.
Angle Converter
Convert between degrees, radians and gradians.
Frequency Converter
Convert between hertz, kilohertz, megahertz and gigahertz.
Why use UnitUtils?
Exact constants
Each unit is defined the way the standards define it: the inch as exactly 25.4 mm, the pound as exactly 0.45359237 kg, the US and imperial gallon as different units. Every page shows the factor it uses.
Private and instant
Conversions run in your browser as you type. Nothing you enter is sent anywhere, and there is nothing to sign up for.
Made for a phone
Large controls, a number keypad, and a swap button. Every page works with a keyboard and a screen reader, and the results can be copied.
Conversions with their own page
Kilograms to Pounds Convert kilograms to pounds quickly and accurately. Pounds to Kilograms Convert pounds to kilograms quickly and accurately. Kilograms to Stones Convert kilograms to stones quickly and accurately. Stones to Kilograms Convert stones to kilograms quickly and accurately. Feet to Metres Convert feet to metres quickly and accurately. Metres to Feet Convert metres to feet quickly and accurately. Inches to Centimetres Convert inches to centimetres quickly and accurately. Centimetres to Inches Convert centimetres to inches quickly and accurately. Miles to Kilometres Convert miles to kilometres quickly and accurately. Kilometres to Miles Convert kilometres to miles quickly and accurately. Miles per Hour to Kilometres per Hour Convert miles per hour to kilometres per hour quickly and accurately. Kilometres per Hour to Miles per Hour Convert kilometres per hour to miles per hour quickly and accurately. Litres to US Gallons Convert litres to US gallons quickly and accurately. US Gallons to Litres Convert US gallons to litres quickly and accurately. Celsius to Fahrenheit Convert degrees Celsius to degrees Fahrenheit quickly and accurately. Fahrenheit to Celsius Convert degrees Fahrenheit to degrees Celsius quickly and accurately.
Measurement guides
Explanations of the units that cause most mistakes, with worked examples. See all guides.
- US and imperial units Why a gallon, a pint and a ton are different sizes in the US and the UK, which units the two systems share, and how to tell which one a recipe, fuel figure or label means.
- Stones and pounds How the stone works for body weight, how to convert between kilograms and stones and pounds by hand, and why 11.5 stone is not 11 stone 5 pounds.
- Temperature scales How the three temperature scales are defined, why converting between them needs an offset as well as a factor, and why a temperature difference converts differently from a reading.
- Speed units How the common speed units relate, where each is used, the exact factors behind them, and what a knot or an airspeed figure does and does not tell you.
- Horsepower and power Why there are several horsepowers, how to convert engine power between kilowatts and horsepower, and the difference between power and energy.
- Metric prefixes and data How SI prefixes scale units from nano to tera, why a 1 TB drive shows as about 931 GB, and how to turn internet speeds in bits into download sizes in bytes.
Unit converters that say which unit they mean
Most conversion mistakes come from a unit name that means more than one thing. A gallon is 3.785 litres in the US and 4.546 litres in the UK. A ton can be 1,000, 907 or 1,016 kilograms. A "GB" on a drive label and a "GB" in an operating system are not the same size. UnitUtils keeps these apart: the volume converter separates US and imperial units, the weight converter has three kinds of ton, and the data storage converter has decimal and binary units side by side.
For the everyday questions there are pages of their own: kilograms to pounds, feet to metres, miles to kilometres, mph to km/h and Celsius to Fahrenheit, each with the formula, a table of common values and the cases where the answer is easy to get wrong.
A few results need care. Temperatures start at different points, so they cannot be converted by multiplying alone. Months and years are not fixed lengths, so the time converter labels them as averages. Where a conversion has a catch, the page says so, and the methodology lists the definition behind every factor.