Unit Converter — Length, Weight, Temperature & Volume Free
Enter a value and pick a unit to see instant conversions across all related units. Covers length (mm to miles), weight (mg to tonnes), temperature (°C, °F, K), and volume (ml to gallons). Everything runs in your browser — nothing is sent to any server.
How it works
- 1 Choose a measurement category Select Length, Weight, Temperature, or Volume from the category dropdown at the top.
- 2 Enter a value and pick the source unit Type the number you want to convert into the value field, then choose your starting unit from the dropdown beside it.
- 3 Read the results All equivalent values appear instantly in the grid below. The highlighted card shows your input unit. Copy any result you need.
Your data stays private
All processing happens entirely in your browser. No files, text, or data are ever sent to our servers. You can disconnect from the internet and this tool will still work.
Frequently asked questions
- What units does the converter support?
- Length: mm, cm, m, km, in, ft, yd, mi. Weight: mg, g, kg, t, oz, lb, st. Temperature: °C, °F, K. Volume: ml, l, tsp, tbsp, fl oz, cup, pt, qt, gal.
- Are the conversions exact?
- All conversion factors are exact by definition (e.g. 1 inch = 0.0254 m exactly). Results are displayed to 7 significant figures. Floating-point rounding may affect the last digit for very large or very small values.
- How do I convert temperature?
- Select Temperature from the category dropdown, type your value, and choose Celsius, Fahrenheit, or Kelvin. The other two values update instantly.
- What is the difference between weight and mass?
- Strictly, kilograms measure mass and pounds measure force (weight). In everyday use the terms are interchangeable, and our converter treats them as such using standard conversion factors.
- Does this use US or UK gallons?
- US gallons (1 gal = 3.78541 l). UK imperial gallons are larger (4.54609 l). If you need UK gallons, multiply the US gallon result by 0.8327.