Unit Converter.

Convert between metric and imperial units of length, mass, and temperature. Pick a category, type a number into either side, and the matching value updates immediately. The converter handles millimeters through kilometers and inches through miles for length; milligrams through metric tons and ounces through US short tons for mass; and Celsius, Fahrenheit, and Kelvin for temperature.

Common reasons to reach for this: reading a recipe written in the other system, sizing hardware against a datasheet from a different region, sanity-checking a workout target in the unit you don’t think in, or filing paperwork that demands a specific representation. The conversion tables follow the 1959 international yard-and-pound agreement and the BIPM SI brochure, so a result here matches what an engineering reference would give.

All work happens in your browser. No values are sent anywhere. Read the full explainer for the precise factors, the affine quirk of temperature, and why “mass” is the honest label for what most people call “weight.”