Unit Converter

Unit Converter - Convert Length, Weight, Temperature & Volume Instantly

Whether you're following a recipe with US measurements, checking a weather forecast in an unfamiliar unit, converting a shipping weight, or working out a project's dimensions, unit conversion is one of the most common small tasks on the internet. This converter covers the four unit types people need most - length, weight, temperature, and volume - with both metric and imperial (US customary) units, updating live as you type.

Metric vs. Imperial: Why Two Systems Exist

The metric system (used by nearly every country except the United States, Liberia, and Myanmar) is based on powers of 10, making conversions within it simple - 1 km = 1,000 m = 100,000 cm. The imperial/US customary system (feet, pounds, gallons) uses less consistent ratios rooted in historical measurement practices, which is exactly why cross-system conversion - like miles to kilometers or pounds to kilograms - needs a calculator rather than mental math.

A Note on Temperature Conversion

Unlike length, weight, and volume, temperature conversion is not a simple multiplication - it involves both a scaling factor and an offset, because the zero points of Celsius, Fahrenheit, and Kelvin scales don't align. Celsius and Fahrenheit famously cross at -40° (that is, -40°C equals exactly -40°F), which is a handy fact to remember when sanity-checking a conversion.

US Customary vs. UK Imperial Volume

One frequent source of confusion: a "gallon," "pint," or "cup" means a different amount depending on whether you're using US customary units or UK imperial units. A US gallon (3.785 L) is about 20% smaller than a UK imperial gallon (4.546 L), and a US pint is about 17% smaller than a UK pint. This calculator uses US customary volume units, which are standard in American recipes, fuel economy figures, and most US-published content.