Weight Converter

Mass is the amount of matter in an object — a fundamental physical property that doesn't change with location. Weight is the gravitational force on that mass, which does vary (you'd weigh less on the Moon, more on Jupiter). In everyday English the two words are used interchangeably, and in everyday contexts on Earth that's fine — but precision matters in physics and engineering. The SI base unit of mass is the kilogram, defined since 2019 by fixing Planck's constant rather than by a physical artifact. Common units span eight orders of magnitude: a carat (200 mg) for gemstones, a gram for food labels, a kilogram for groceries, a stone (14 lb) for British body weight, a ton for shipping, a tonne for cargo. This Weight Converter handles 13 units at once with the official factors. Need linear measurement? Use the Length Converter. Working with capacity? Try the Volume Converter.