Unit converter
76 categories, 504 units. Every number on this site comes out of one table, so no two pages can disagree.
Pick a category
LengthDistance, from nanometres to light years.
Weight and MassMass, from micrograms to tons.
VolumeCapacity, including the kitchen measures that differ between countries.
TemperatureCelsius, Fahrenheit and Kelvin. The only common category where you cannot just multiply.
AreaSurface area, from square millimetres to square miles.
PressureForce per unit area, for tyres, weather and engineering.
EnergyEnergy and work, including the two different calories.
PowerRate of energy, including the three different horsepowers.
ForceNewtons, pounds-force and the units engines are rated in.
TimeFrom nanoseconds to centuries.
SpeedHow fast, in every unit people actually use.
AngleDegrees, radians and the ones surveyors use.
Fuel economyMiles per gallon, kilometres per litre and litres per 100 km — two of which run backwards from the third.
Data StorageBytes, and the decimal-versus-binary difference that makes your drive look smaller.
Volume (dry)Dry measure — a different family from liquid pints and quarts.
Every converter
76 categories, grouped so a wall of links stays readable.
Common converters
Magnetism converters
Light converters
Engineering converters
Fluids converters
Radiology converters
Other converters
Heat converters
Electricity converters
- Electric charge converter
- Linear charge density converter
- Surface charge density converter
- Volume charge density converter
- Electric current converter
- Linear current density converter
- Surface current density converter
- Electric field strength converter
- Voltage converter
- Electric resistance converter
- Electric resistivity converter
- Electric conductance converter
- Electric conductivity converter
- Capacitance converter
- Inductance converter
Why another one of these
Most converters hand you a number with no idea how much to trust it. A US cup and an imperial cup are different sizes. A food calorie is a thousand physics calories. A "1 TB" drive reports 931 GB. Mach 1 is slower when it is cold. Three different horsepowers are in daily use and they disagree.
Every unit here carries a line saying what it actually is — exact by definition, an average, or something that shifts with conditions. That line is usually the answer you came for.