Convert length, weight and temperature in one place. Change metres to miles, kilograms to pounds, or Celsius to Fahrenheit — fast, free and accurate.
Use the first box for length, the second for weight and the third for temperature. Enter a value, choose the units, and click Convert.
A unit converter changes a measurement from one unit into another. The world uses two main systems: the metric system (metres, kilograms, Celsius), used in most countries, and the imperial system (miles, feet, pounds, Fahrenheit), used mainly in the USA. Recipes, schoolwork, travel, shopping and DIY all mix the two systems, so a converter is useful every day. This free unit converter handles the three conversions people need most: length, weight and temperature, with no sign-up and no download.
Unit conversion matters because a wrong unit can ruin a result. A recipe that needs 500 grams of flour will fail with 500 pounds. A road sign that says 5 miles means about 8 kilometres, not 5. A fever of 100 degrees Fahrenheit is not the same as 100 degrees Celsius. Checking the conversion first saves mistakes in cooking, travel, study and work.
Length: 5 kilometres is 5 times 1,000 divided by 1,609.34, which is about 3.11 miles. Weight: 10 kilograms is 10 divided by 0.453592, which is about 22.05 pounds. Temperature: 100 degrees Celsius is 100 times 9 divided by 5 plus 32, which is 212 degrees Fahrenheit, the boiling point of water. And 0 degrees Celsius is 32 degrees Fahrenheit, the freezing point of water. Try your own numbers in the three boxes above.
Length and weight conversions use a fixed factor. The converter first changes your value into a base unit (metres for length, kilograms for weight), then changes it into the unit you want. For example, 1 mile is 1,609.34 metres, 1 foot is 0.3048 metres, 1 pound is 0.453592 kilograms, and 1 ounce is 0.0283495 kilograms. Temperature is different because the scales start at different points: Celsius to Fahrenheit is (C times 9 divided by 5) plus 32, and Celsius to Kelvin is C plus 273.15.
Check the unit before you cook. Baking recipes are sensitive, so convert grams and cups carefully and use a kitchen scale when you can. Remember the rough guides. One mile is about 1.6 kilometres, one kilogram is about 2.2 pounds, and one inch is about 2.5 centimetres. Use Celsius for weather. Most of the world reports weather in Celsius: 20 degrees is mild, 30 degrees is hot, and 0 degrees is freezing. Double-check heights and weights. Medical forms and visa applications often ask for height in feet and inches or weight in pounds, so convert before you write them down. Keep the result's units. Always write the unit with the number, because a number without a unit can be misunderstood.
Here are three conversions to try in the boxes above. First, a 10-mile run is 10 times 1.60934, which is 16.09 kilometres. Second, a bag of flour weighing 5 kilograms is 5 times 2.20462, which is 11.02 pounds. Third, water boils at 100 degrees Celsius, which is 212 degrees Fahrenheit, and it freezes at 0 degrees Celsius, which is 32 degrees Fahrenheit. Notice that temperature is different from length and weight: it needs adding and subtracting as well as multiplying, so the formula is different.
Mixing up miles and kilometres. A mile is longer than a kilometre: 1 mile is about 1.61 kilometres, so 10 miles is 16 kilometres, not 10 kilometres. Forgetting temperature is different. Celsius and Fahrenheit do not start at the same zero, so you cannot convert them by multiplying alone. Using the wrong pound. A pound is a unit of weight, but the British pound is also money; this converter uses the weight meaning. Rounding too early. Keep the full conversion factor while you calculate and round only the final answer. Trusting a rough guess. "About 2 pounds per kilogram" is fine for shopping, but not for medicine or science, where the exact factor matters.
Pro Tip: Learn a few handy facts: 1 kilometre is about 0.62 miles, 1 kilogram is about 2.2 pounds, and 1 litre is about 0.26 gallons. They cover most everyday conversions.
Note: This converter uses exact standard factors, such as 1 inch = 2.54 centimetres and 1 pound = 0.45359237 kilograms, so its results match scientific references.
How many kilometres are in a mile? One mile is 1.60934 kilometres. So 5 miles is about 8.05 kilometres, and 10 kilometres is about 6.21 miles.
How many pounds are in a kilogram? One kilogram is about 2.20462 pounds. So 10 kilograms is about 22.05 pounds, and 50 pounds is about 22.68 kilograms.
How do I convert Celsius to Fahrenheit? Multiply the Celsius temperature by 9, divide by 5, and add 32. For example, 20 degrees Celsius is 68 degrees Fahrenheit.
What is the difference between mass and weight? In everyday use they mean the same thing, and this converter treats kilograms, grams, pounds and ounces as units of weight. Scientists use "mass" for the amount of matter and "weight" for the force of gravity, but the numbers are the same on Earth.
Can I convert other units, like volume or area? Not yet. This converter covers length, weight and temperature, which are the most searched conversions. More unit types may be added later.
Is this unit converter free? Yes, it is completely free, with no sign-up and no limit on how many conversions you make.
Why is temperature conversion different? Because Celsius and Fahrenheit have different zero points: water freezes at 0 degrees Celsius but at 32 degrees Fahrenheit, so the formula must add or subtract 32 as well as multiply.