Unit Converter Online Free
Convert between all major units: km to miles, kg to lbs, Celsius to Fahrenheit, litres to gallons instantly.
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About Unit Converter
Convert between length (km, m, cm, miles, feet, inches), weight (kg, g, lb, oz), temperature (°C, °F, K), and volume (L, ml, gallon, cup).
Unit conversion errors have caused real, well-documented failures — NASA's Mars Climate Orbiter was lost in 1999 specifically because of a mismatch between metric and imperial unit calculations between two engineering teams — which is a useful reminder that even simple length, weight, or temperature conversions deserve a reliable tool rather than manual arithmetic. This converter covers the everyday cases people actually run into: metric-to-imperial length and weight conversions for cooking, travel, or international shopping, and temperature conversion between Celsius and Fahrenheit, which trips people up constantly since the two scales aren't proportional (0°C is 32°F, not 0°F). All conversions use precise, internationally standardized conversion factors rather than rounded approximations.
How to use
- Enter a value and pick your source and target units — the conversion updates instantly.
- Double-check the unit abbreviations shown, since similarly-named units sometimes use different base definitions.
- Use the swap or reverse option if available to quickly flip the conversion direction.
- Chain into a related converter below if your task needs a second conversion step.
- All conversions are computed in your browser using standard, precise conversion factors.
Tool details
⚡ Next step — complete your workflow
Frequently asked questions
Cm in an inch?
1 inch = 2.54 cm exactly. 1 foot = 30.48 cm. 1 meter = 39.37 inches.
Celsius to Fahrenheit?
°F = (°C × 9/5) + 32. Key: 0°C=32°F, 100°C=212°F, 37°C=98.6°F.
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