Recipes in cups, a road sign in miles, a parcel weighed in pounds, an oven set in Fahrenheit. Sooner or later you run into a measurement that isn’t in the units you’re used to. This converter switches between units in one step, so you don’t have to dig out a formula or trust a half-remembered rule of thumb.
Pick the type of measurement, such as length, weight, temperature, volume, area or speed.
Enter the number you want to convert.
Choose the unit you’re starting from and the one you want.
Read the result. It updates as soon as you change a value.
You can use decimals, and you can swap the two units at any time to convert in the other direction.
Length: millimetres, centimetres, metres, kilometres, inches, feet, yards, miles
Weight: grams, kilograms, ounces, pounds
Temperature: Celsius, Fahrenheit, Kelvin
Volume: millilitres, litres, teaspoons, tablespoons, cups, fluid ounces, gallons
Area: square metres, square feet, hectares, acres
Speed: km/h, mph, metres per second, knots
Most conversions are plain multiplication. Here are the ones people use most:
1 inch = 2.54 centimetres
1 mile = 1.609 kilometres
1 kilogram = 2.205 pounds
1 ounce = 28.35 grams
1 litre = 0.264 US gallons
Temperature is the odd one out, because the scales start at different points:
Celsius to Fahrenheit: °F = °C × 9/5 + 32
Fahrenheit to Celsius: °C = (°F − 32) × 5/9
Celsius to Kelvin: K = °C + 273.15
Distance. A road sign says a town is 50 miles away. 50 × 1.609 = 80.5, so it’s about 80 kilometres.
Cooking. A recipe calls for 2 cups of milk. One US cup is about 237 millilitres, so 2 cups is roughly 474 ml.
Temperature. An oven set to 350°F is (350 − 32) × 5/9 = 176.7, so around 177°C.
Weight. You weigh 165 pounds. 165 ÷ 2.205 = 74.8, so about 75 kilograms.
Not every gallon is the same size. A US gallon is about 3.79 litres, while an imperial (UK) gallon is about 4.55 litres. Check which one your source means.
Ounces come in two kinds. Weight ounces and fluid ounces measure different things, so they aren’t interchangeable.
Cups vary. A US cup is about 237 ml, but a metric cup is 250 ml, and in some countries a cup means something else again. For baking, weighing ingredients is more reliable.
Don’t convert temperature by simple multiplication. Doubling a Celsius figure won’t give you Fahrenheit. Use the formula above.
How accurate are the results?
Conversions use standard factors and are shown with several decimal places. For everyday use that’s more than enough. For engineering, science or legal work, check the exact figure you need against an official source.
Why does my result have so many decimals?
Most unit relationships don’t divide neatly. Round the result to whatever suits the job: a couple of decimals for cooking, none at all for a rough distance.
Can I convert between different types, like kilograms to litres?
No. Weight and volume measure different things, and the link between them depends on the material. A litre of water weighs about a kilogram, but a litre of honey weighs much more.
What’s the quickest way to estimate kilometres from miles?
Multiply by 1.6, or add half and a little more. 10 miles is roughly 16 km.
Do I need to create an account or install anything?
No. Open the page, type your numbers and you’re done.
Results are approximate and meant for general use. For professional, scientific or legal purposes, verify the figures against an official source.