Unit Conversion Calculators
Length, weight, volume, temperature, speed, energy, currency and more — every unit conversion you will ever need, with the formula always shown.
Why Unit Conversion Accuracy Matters
Unit conversion errors have caused some of history's most expensive mistakes — from NASA's Mars Climate Orbiter crash (a $327 million loss due to a metric/imperial mix-up) to pharmaceutical dosing errors that cost lives. In everyday life the stakes are lower, but accuracy still matters whether you are following a recipe, planning a road trip, calculating fuel efficiency, or doing engineering work.
Our unit converters cover every major measurement system — metric, imperial, US customary, and scientific — and always display the exact conversion factor used. This means you can verify every result and understand the relationship between units, not just get a number to copy.
Every converter works on any device, loads instantly, and is completely free to use without registration.
Length & Distance Converters
Metres, feet, miles, kilometres, inches, yards — every length and distance conversion instantly.
Metres to Feet Converter
Convert any length from metres to feet
Kilometres to Miles Converter
Distance conversion with exact factor displayed
Feet to Metres Converter
Imperial to metric length conversion
Acres to Square Feet Converter
Land area from acres to square feet
Acres to Hectares Converter
Agricultural and land area conversion
Inches to Centimetres Converter
Precise inch to centimetre conversion
Weight & Mass Converters
Kilograms, pounds, ounces, stones, grams — every weight conversion with full formula display.
Kilograms to Pounds Converter
Convert any weight from kg to lbs instantly
Pounds to Kilograms Converter
Imperial to metric weight conversion
Grams to Ounces Converter
Cooking and postal weight conversions
Stone to Kilograms Converter
UK stone measurement to metric kilograms
Ounces to Grams Converter
US to metric cooking weight conversion
Tonnes to Pounds Converter
Metric tonnes to US/Imperial pounds
Temperature Converters
Celsius, Fahrenheit, Kelvin and Rankine — every temperature scale conversion with formula shown.
Celsius to Fahrenheit Converter
C to F conversion with exact formula
Fahrenheit to Celsius Converter
F to C conversion for cooking and weather
Celsius to Kelvin Converter
Metric to absolute temperature scale
Fahrenheit to Kelvin Converter
Direct F to K scientific conversion
Absolute Zero Converter
Convert absolute zero across all temperature scales
Oven Temperature Conversion Calculator
Gas mark, fan, conventional — all oven temps
Speed Converters
MPH, KPH, knots, m/s — speed and velocity conversions for travel, aviation, and science.
MPH to KPH Converter
Miles per hour to kilometres per hour
KPH to MPH Converter
Kilometres per hour to miles per hour
Knots to MPH Converter
Nautical to land speed conversion
MPH to M/S Converter
Miles per hour to metres per second
Fuel Economy MPG to L/100km
US MPG to European L/100km conversion
Wind Speed Converter
Beaufort scale, MPH, KPH and m/s
Unit Conversion FAQ
Convert Anything Instantly.
515+ unit converters covering every measurement system. Free, instant, with the conversion formula always displayed.