Unit Converter
Convert length, mass, temperature, area, volume and speed units.
Unit Converter — Convert between metric and imperial units across six dimensions: length, mass, temperature, area, volume and speed. Temperature handles the non-linear °C/°F/K formulas correctly, and results are formatted for your locale. All math happens instantly in your browser.
What is Unit Converter?
The Unit Converter is a free online tool for converting measurements between metric and imperial units across six categories: length, mass, temperature, area, volume, and speed. Engineers, students, cooks, and travelers use it to quickly change kilometers to miles, kilograms to pounds, Celsius to Fahrenheit, square meters to acres, liters to gallons, or km/h to mph. Pick a category, type a value, choose your From and To units, and the converted result appears instantly in the read-only result field. Temperature uses the correct non-linear °C/°F/K formulas, and results are formatted to your locale with up to six decimal places.
How to use Unit Converter
- Choose a measurement category from the segmented buttons: Length, Mass, Temp., Area, Volume, or Speed.
- In the From section, type the number you want to convert into the value input.
- Below that value, pick the source unit from the From dropdown (for example km, kg, °C, m², l, or m/s).
- In the To section, pick the target unit from the To dropdown.
- Read the converted result instantly in the read-only To field; it updates automatically as you change the value or either unit.
Examples
Length: kilometers to meters
Input
Length, 1 km to m
Output
1,000
Temperature: Celsius to Fahrenheit
Input
Temp., 100 °C to °F
Output
212
Length: inches to centimeters
Input
Length, 1 in to cm
Output
2.54
Frequently asked questions
- Which units and categories are supported?
- Six categories: Length (mm, cm, m, km, in, ft, yd, mi), Mass (mg, g, kg, t, oz, lb), Temperature (°C, °F, °K), Area (mm², cm², m², km², ft², ac), Volume (ml, l, m³, tsp, tbsp, cup, gal), and Speed (m/s, km/h, mph, knot).
- How precise are the conversions?
- Results are computed with standard conversion factors and shown with up to six decimal places, formatted for your locale (so thousands separators and decimal marks match your region).
- Why does temperature convert differently from other units?
- Temperature scales are non-linear and need offset formulas rather than a simple ratio, so the tool applies the correct °C/°F/K equations instead of multiplying by a factor.
- What happens if I enter text or leave the value blank?
- If the input is not a valid finite number, the result field simply shows a dash (—) until you enter a valid numeric value.
- Does my data get uploaded anywhere?
- No. Every conversion runs 100% client-side in your browser with no upload and no server communication, so your values never leave your device.
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