Weight & Mass Converter

This free weight and mass converter converts between every common and scientific unit of mass — microgram, milligram, carat, grain, gram, dram, ounce, troy ounce, pound, kilogram, stone, hundredweight, short (US) ton, metric tonne, long (imperial) ton, slug and the atomic mass unit (dalton). Type a value, pick your units, and the result, the exact formula and a full "in every unit" table update instantly.

Unlike most converters, you can control precision directly: choose Auto for a clean trimmed result or lock 0–10 decimal places, and toggle thousands separators for large values. Copy any single result or the whole table with one click, and swap the two units instantly. Conversions use exact SI-derived factors (1 lb = 453.592 37 g, 1 oz = 28.349 523 125 g, 1 stone = 6350.293 18 g), so kg to lbs, grams to ounces, stone to kg and pounds to kg all round-trip accurately.