Free Unit Converter

Select a category (length, weight, temperature, etc.), choose your 'from' and 'to' units from the dropdowns, type in your value, and the result appears instantly. You can also swap the two units with the arrow button.

Most unit conversions are simple multiplication. Temperature is different because the Celsius, Fahrenheit, and Kelvin scales don't share the same zero point. Fahrenheit and Celsius have offset origins, so the formula involves both multiplication and addition/subtraction.

There are exactly 2.54 centimeters in one inch. This is a defined, exact conversion. So 1 foot = 12 inches = 30.48 centimeters, and 1 meter = 100 cm = approximately 39.37 inches.

Mass is the amount of matter in an object (measured in kg or lbs) and doesn't change based on location. Weight is the gravitational force on that mass, which varies by location. In everyday use, people use 'weight' when they really mean 'mass' — so this calculator treats them as equivalent.

All conversions use precise, internationally defined conversion factors. Results are shown to up to 8 significant figures. For scientific or engineering use, always verify critical conversions with primary reference sources.

A knot is one nautical mile per hour, approximately 1.852 km/h or 1.151 mph. It's the standard unit used in maritime and aviation navigation, based on the nautical mile which is defined as one minute of arc along a meridian of the Earth.