Convert between commonly used units of length, temperature, area, volume, and weight. Enter a value, choose the current unit and the unit you want, and read the result plus a table of every equivalent in that category.
Units by category
| Category | Base unit | Examples |
|---|---|---|
| Length | Meter | Kilometer, Foot, Inch, Mile, Light Year |
| Temperature | Celsius | Kelvin, Fahrenheit |
| Area | Square Meter | Hectare, Acre, Square Foot, Square Mile |
| Volume | Cubic Meter | Liter, US Gallon, Imperial Gallon, Cubic Foot |
| Weight | Kilogram | Gram, Pound, Ounce, Carrat, Metric Ton |
Examples
1 meter to kilometers and feet
1 Meter = 0.001 Kilometer and 3.280839895 Foot. 100 Yard = 300 Foot; 5.5 Foot = 66 Inch.
25 C to Kelvin and Fahrenheit
25 Celsius = 298.15 Kelvin and 77 Fahrenheit. 0 Celsius = 32 Fahrenheit; 100 Celsius = 212 Fahrenheit; 32 Fahrenheit = 0 Celsius.
1 kilogram and 1 pound
1 Kilogram = 1000 Gram and 2.2046244202 Pound. 1 Pound = 0.453592 Kilogram and 16 Ounce.
Formula
Each category reduces to one base unit, then expands into the target unit:
base = toBase(from unit, value)
result = fromBase(to unit, base)
Linear units use a constant factor (value × factor to the base, then ÷ factor from the base). Temperature is affine:
Celsius = value
Kelvin = value − 273.15 (to Celsius)
= value + 273.15 (from Celsius)
Fahrenheit = 5/9 × (value − 32) (to Celsius)
= 9/5 × value + 32 (from Celsius)
Conversion limits
Defined SI and international-foot conversions use fixed factors; temperature uses an affine formula rather than a simple multiplier. Results are rounded for display, so converting a displayed answer back can differ in the last digits. Context-dependent units such as fuel economy, cooking measures, survey units, and nominal product sizes require the convention named by the source. NIST SP 811 documents SI usage and conversion practice.
Measurements, money, and rounded answers
Unit factors describe fixed measurement relationships. Money conversion uses changing exchange rates instead: use the Currency Calculator and check the quote date. To apply a particular rounding rule after a conversion, use the Rounding Calculator, keeping extra digits until the last step.
Choose a measurement-specific converter
For mixed feet and inches, use the Length and Height Converter. For stone/pounds, pounds/ounces, micrograms or troy mass, use the Mass and Weight Converter. The Area Converter adds land units and the Liquid Volume Converter labels US and imperial gallons separately. Each includes an all-unit table and worked examples.