Weight measurement involves three primary systems — metric (kilograms and grams), US customary / imperial (pounds and ounces), and troy (used exclusively for precious metals) — each with distinct scales and conversion factors. The kilogram, redefined in 2019 by the General Conference on Weights and Measures in terms of the Planck constant rather than a physical artifact, is the SI base unit of mass used by every country except the United States, Myanmar, and Liberia for everyday commerce. One kilogram equals 2.20462 pounds, and one pound equals 16 ounces (453.592 grams). The troy system adds confusion: a troy ounce (31.1035 g) is heavier than an avoirdupois ounce (28.3495 g), which is why gold quoted at $2,300 per ounce refers to a troy ounce. In cooking, metric recipes specify grams while American recipes use cups and ounces — a conversion that depends on ingredient density (1 cup of flour weighs about 125 g, while 1 cup of sugar weighs about 200 g). Medical dosing uses kilograms exclusively, making accurate kg-to-lb conversion critical for patient safety. Whether you are shipping internationally, following a foreign recipe, tracking fitness metrics, or trading commodities, precise weight conversion prevents errors that can be costly or even dangerous.
Metric vs Imperial Weight Units
Metric units (mcg, mg, g, kg, tonne) scale by powers of 10 around the kilogram, the SI base unit of mass. Imperial / US units (ounce, pound, stone, ton) use legacy ratios: 16 oz = 1 lb, 14 lb = 1 stone, 2,000 lb = 1 US (short) ton, 2,240 lb = 1 UK (long) ton. Cross-system conversions use fixed factors — 1 lb = 453.59237 g, 1 oz = 28.349523125 g, 1 metric tonne = 1,000 kg ≈ 2,204.62 lb. Our weight converter handles both systems bidirectionally with no rounding surprises.
Specialty Mass Units
Beyond everyday units, this tool supports troy ounces (31.1034768 g) for precious metals like gold and silver, carats (0.2 g) for gemstones and diamonds, grains (64.79891 mg) for bullets, arrows, and pharmaceuticals, and micrograms (10⁻⁶ g) for medicine dosing and lab work — all converted through grams as the common base. Whether you are pricing gold, measuring a diamond, estimating shipping weight, or converting a cooking recipe, the weight converter gives you an instant, accurate answer.