Unit Converter

Most of the world uses the metric system (meters, kilograms, Celsius), a decimal-based system where units scale by powers of ten. The United States — and, in everyday contexts, the UK — still uses imperial units (miles, pounds, Fahrenheit). This split means unit conversion remains a daily necessity: travelers convert road distances and temperatures, online shoppers convert product weights and dimensions, cooks convert recipe measurements, and engineers convert specifications between standards.

The conversion factors used here are the exact values fixed by international agreement: one inch is exactly 2.54 cm, one pound is exactly 0.45359237 kg, and one mile is exactly 1,609.344 meters. Temperature is the one category where conversion is not a simple multiplication — Fahrenheit and Celsius have different zero points, so the formula involves both scaling and shifting: °F = °C × 9/5 + 32.

A few approximations cover most everyday needs. Length: a kilometer is about 0.62 miles, so a 10K run is roughly 6.2 miles; a meter is about 3.28 feet; an inch is 2.54 cm exactly. Weight: a kilogram is about 2.2 pounds, so an 80 kg person weighs roughly 176 lb; an ounce is about 28 grams. Temperature: 0°C is freezing (32°F), 100°C is boiling (212°F), body temperature is 37°C (98.6°F), and a comfortable room is around 21°C (70°F). A rough mental shortcut for Celsius to Fahrenheit is to double the number and add 30 — accurate to within a few degrees across the everyday range.

For anything where precision matters — engineering, medicine, shipping costs, legal documents — skip the shortcuts and use the exact converter above.