Free Online Unit Converter
Convert length, weight, temperature, area, volume, speed, and more with real-time results.
Millimeters (mm) → Centimeters (cm). Linear conversion relative to a base unit.
What is Unit Converter?
A unit converter translates a measurement from one unit to another within the same category — for example centimeters to inches, kilograms to pounds, or Celsius to Fahrenheit. It relies on fixed conversion factors for linear units and special formulas for temperature, area, volume, and data storage. This free metric converter covers length, weight, temperature, area, volume, speed, data storage, and time, with live two-way results. Whether you need a quick kg to lbs conversion, a cm to inches lookup, or a Celsius to Fahrenheit check, the tool updates instantly as you type.
How to use it
- Select the category you want to convert (length, weight, temperature, and so on).
- Choose the 'from' and 'to' units using the dropdowns.
- Type a value — the result updates in real time.
- Use the swap button to reverse the direction instantly.
How conversions work
Linear units convert via a fixed factor relative to a base unit (for length, the meter). Temperature uses dedicated formulas: °F = °C × 9/5 + 32 and K = °C + 273.15. Data storage uses the 1024-based binary scale for KB, MB, GB, and TB.
Frequently asked questions
Multiply the length in centimeters by 0.393701, or divide by 2.54. For example, 10 cm ÷ 2.54 = 3.94 inches. This converter applies the factor automatically.
Multiply kilograms by 2.20462. For example, 70 kg × 2.20462 = 154.32 lb. To go the other way, divide pounds by 2.20462.
Use the formula °F = °C × 9/5 + 32. Water freezes at 0°C (32°F) and boils at 100°C (212°F). The temperature converter applies this automatically.
The metric system uses base-10 units (meters, grams, liters) used by most of the world. The imperial system uses inches, feet, pounds, and gallons, common in the United States.
This converter uses the binary scale where 1 KB = 1024 bytes, 1 MB = 1024 KB, and so on. Storage manufacturers sometimes use the decimal 1000 scale, which is why a '1 TB' drive shows fewer bytes in your operating system.
Temperature scales do not share a zero point, so a simple multiplication does not work. Celsius and Fahrenheit both have different freezing points, requiring the offset formula rather than a single factor.
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