A unit converter is a free online tool that translates measurements between metric and imperial systems. Switch tabs for length, weight, temperature, area, volume, speed and fuel economy to get instant, accurate conversions with full comparison tables, with no signup.
How do you convert between metric and imperial units?
Multiply by the exact defined factor: inches to centimeters uses 2.54, miles to kilometers uses 1.609344, and pounds to kilograms uses 0.45359237. These are international definitions, not approximations, so results are exact before rounding. The converter above applies them instantly.
Pick the tab above, enter your value, and the converter applies the factor instantly. The full table shows every unit in the category at once, which is handy for recipes, DIY projects and shipping labels.
What is the formula to convert Fahrenheit to Celsius?
Subtract 32, then multiply by 5/9: C = (F - 32) x 5/9. So 68 F becomes 20 C. To go the other way, multiply by 9/5 and add 32: F = C x 9/5 + 32. Temperature needs these offset formulas because the scales start at different zeros.
Temperature is special because the scales start at different zeros, which is why a simple multiplier fails. The converter above applies the correct offset formulas and rejects impossible values below absolute zero (-273.15 C).
How do you convert mpg to liters per 100 km?
Divide 235.214583 by the mpg figure: L/100km = 235.214583 / mpg. So 30 mpg equals about 7.84 L/100km. Note the relationship is inverse: higher mpg means lower L/100km. The fuel tab handles this plus km/L conversions automatically. Try it with your own car's window-sticker figure.
The fuel economy tab handles this plus km/L conversions, useful when comparing American and European car specifications or rental listings abroad.
Why do conversion results show so many decimals?
The tool computes with full precision and displays up to 6 significant decimals so rounding never corrupts chained calculations. For everyday use like cooking or carpentry, round to 1 or 2 decimals yourself; engineering work should keep the extra digits.
Engineering and scientific work should keep the extra digits; the underlying factors (like 0.3048 m per foot) are exact by international agreement.
FAQs
Is this unit converter free?
Yes. Convert as many values as you like across all seven categories with no account and no limits.
How accurate are the conversions?
Factors use internationally defined exact values, such as 1 inch = 2.54 cm and 1 pound = 0.45359237 kg, with results rounded to 6 significant decimals for display.
How do I convert mpg to L/100km?
Open the Fuel economy tab, enter your mpg, and read the L/100km value. The formula is 235.214583 divided by mpg, so 30 mpg equals about 7.84 L/100km.
Why is temperature conversion different?
Temperature scales have different zero points, so conversion needs addition and subtraction, not just multiplication. The tool applies the correct formulas and blocks values below absolute zero.
Does it work offline?
Yes. All conversion factors are built into the page, so once it loads you can convert with no internet connection.