Unit converters with exact factors
Convert between metric, imperial and local units instantly. Each converter shows the exact conversion factor and a table of common values, so you can trust the result and reuse it.
Convert length, weight, temperature and volume, including units such as the tola used for gold in South Asia and the difference between US and UK gallons. For land, the land area converter handles marla, kanal, acres and hectares.
Quick pages for the most common conversions
Most people need the same handful of conversions again and again, so each of these has its own page with the converter already set up, the exact factor, a chart and worked examples: cm to inches, kg to lbs, Celsius to Fahrenheit, km to miles, ml to oz, cm to feet for heights and marla to sq ft for plots. The full list is above.
Why our factors are exact
Most imperial units are now defined from metric ones. Since 1959 an inch has been exactly 2.54 cm and a pound exactly 0.45359237 kg; a US gallon is exactly 3.785411784 litres. We use these definitions (from NIST and the UK Weights and Measures Act) and round only the number you see, so a result converted there and back returns to where it started.