Unit Converter
Convert between units of length, weight, and temperature online, free. Fast, accurate conversions.
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About Unit Converter
Convert everyday measurements between metric and imperial units — length, weight, temperature and more — without looking up the factors yourself.
Useful exact values
Some conversions are exact by definition: one inch is exactly 2.54 centimetres, and one mile is exactly 1.609344 kilometres. Others are rounded: one kilogram is about 2.20462 pounds, so 10 kg is about 22.05 lb.
Temperature works differently
Temperature isn't a simple multiplication, because the two scales start at different points. To turn Celsius into Fahrenheit, multiply by 9/5 and add 32: a normal body temperature of 37 °C is 98.6 °F. To go back, subtract 32 and multiply by 5/9.
Where conversions trip people up
Recipes from the United States use cups and ounces, and a fluid ounce of volume is not the same as an ounce of weight. A US gallon is smaller than a UK gallon, so car fuel figures from different countries don't compare directly. Screen and TV sizes are given in inches measured diagonally. Land in Pakistan is often measured in marla and kanal, whose size varies by region, so check the local standard before converting a plot to square feet.
Precision
Round the result to a sensible number of digits for the job: two decimal places is plenty for a recipe or a parcel, while engineering drawings may need more. Rounding too early in a calculation and then multiplying can add up to a noticeable error.
For converting time between cities, use the World Clock; for screen and image proportions, the Aspect Ratio Calculator.
Useful exact values
Some conversions are exact by definition: one inch is exactly 2.54 centimetres, and one mile is exactly 1.609344 kilometres. Others are rounded: one kilogram is about 2.20462 pounds, so 10 kg is about 22.05 lb.
Temperature works differently
Temperature isn't a simple multiplication, because the two scales start at different points. To turn Celsius into Fahrenheit, multiply by 9/5 and add 32: a normal body temperature of 37 °C is 98.6 °F. To go back, subtract 32 and multiply by 5/9.
Where conversions trip people up
Recipes from the United States use cups and ounces, and a fluid ounce of volume is not the same as an ounce of weight. A US gallon is smaller than a UK gallon, so car fuel figures from different countries don't compare directly. Screen and TV sizes are given in inches measured diagonally. Land in Pakistan is often measured in marla and kanal, whose size varies by region, so check the local standard before converting a plot to square feet.
Precision
Round the result to a sensible number of digits for the job: two decimal places is plenty for a recipe or a parcel, while engineering drawings may need more. Rounding too early in a calculation and then multiplying can add up to a noticeable error.
For converting time between cities, use the World Clock; for screen and image proportions, the Aspect Ratio Calculator.
Frequently Asked Questions
What types of units can I convert?
Length, weight, and temperature conversions are all supported.
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