How to use the units converter
- Pick a category — length, weight, temperature, volume and more.
- Choose your from unit and to unit.
- Type any number. The answer updates as you type.
- Press the swap button to reverse the direction, or Copy to grab the result.
What's inside
- Length — from nanometers to light-years, including metric, imperial and nautical units.
- Weight & mass — milligrams to tonnes, ounces to stone, plus US and UK tons.
- Temperature — Celsius, Fahrenheit and Kelvin with correct offset handling.
- Area, volume, speed, time — square feet to hectares, teaspoons to litres, knots to mach.
- Data — bits to petabytes, using decimal SI prefixes (what drives and networks actually use).
- Pressure, energy, power, angle — bar to PSI, joules to kilocalories, watts to horsepower.
Why 1 [unit] equals panel is useful
Most converters only show one answer at a time. The panel above shows what one of your chosen units equals in every other unit in the same category — so you can see the whole picture at once. Click any tile to set it as the target unit.
Accuracy
All conversions use exact, internationally defined values. For example, 1 inch is defined as exactly 25.4 mm, 1 pound as exactly 0.45359237 kg, and 0°C as exactly 273.15 K. Results are rounded to 10 significant figures, which is more than enough for any practical use.
Common questions
Is this units converter free?
Yes. It is completely free, has no limits and runs entirely in your browser.
Which units can I convert?
Length, weight and mass, temperature, area, volume, speed, time, data, pressure, energy, power and angle — over 100 units in total.
Does it upload my data?
No. All calculations happen locally in your browser using JavaScript. Nothing is sent anywhere, and the tool works offline once loaded.
Why does temperature work differently?
Celsius, Fahrenheit and Kelvin don't share a common zero point, so they need offset arithmetic instead of simple multiplication. The tool handles this correctly.
How accurate are the conversions?
Conversions use internationally defined exact values. Results are shown to 10 significant figures.
Does it work on mobile?
Yes. The tool adapts to any screen size, and numeric input brings up the correct keyboard on phones.