Unit Converter
Convert length, weight, volume, temperature, and speed between common units. Every calculation happens on your device — your numbers are never sent anywhere.
| Unit | Value |
|---|---|
| Millimeters (mm) | 25.4 |
| Centimeters (cm) | 2.54 |
| Meters (m) | 0.0254 |
| Kilometers (km) | 0.000025 |
| Feet (ft) | 0.083333 |
| Yards (yd) | 0.027778 |
| Miles (mi) | 0.000016 |
How to use this tool
- Pick a category: length, weight, volume, area, temperature, or speed.
- Enter the amount you want to convert.
- Choose the units to convert from and to — the result updates instantly.
- Use the swap button to reverse the conversion, and the table below to see your value in every unit at once.
How it works
Each unit is defined by a fixed conversion factor to a base unit (meters for length, kilograms for weight, liters for volume). Your value is multiplied into the base unit and divided out into the target unit, so conversions are exact to the precision shown.
Temperature is the exception: Celsius, Fahrenheit, and Kelvin use offset formulas (°F = °C × 9/5 + 32; K = °C + 273.15) rather than simple factors.
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Frequently asked questions
How many centimeters are in an inch?
Exactly 2.54 cm. This is a defined value, not an approximation — so 10 inches is exactly 25.4 cm.
How do I convert Fahrenheit to Celsius?
Subtract 32, then multiply by 5/9. For example, 98.6°F − 32 = 66.6, and 66.6 × 5/9 = 37°C.
Are US and UK measurements different?
Some are. This tool uses US customary units for volume (cups, pints, gallons); UK imperial pints and gallons are about 20% larger. Length and weight units (inches, feet, pounds) are the same.
How precise are the results?
Results are shown to up to 6 significant decimal places depending on magnitude. The underlying math uses full floating-point precision.