Weight Converter

Weight conversions bridge the metric system — grams and kilograms, based on the kilogram as the SI base unit — and the imperial/US system of ounces, pounds, and stone. The pound is formally defined as exactly 0.45359237 kilograms, and an ounce is one sixteenth of a pound, so the underlying math is fixed and exact rather than a rounded approximation.

This gets used constantly for cooking (recipes from different countries list ingredients in grams or ounces), reading shipping and luggage weight limits, tracking body weight against a scale that uses a different unit, and comparing product specs listed in kilograms versus pounds.

Note that 'weight' here really means mass, not the technical physics definition of weight as a force — the distinction almost never matters at Earth's surface, but it's why scientists prefer the word mass. Also worth knowing: the UK and Ireland commonly express body weight in stone (14 pounds). Stone isn't one of the units listed here, so convert to pounds first and then divide by 14 to get the stone figure.