scale Weight & Mass Unit Converter star

How It Works

Enter a value in any unit — milligrams, grams, kilograms, tonnes, ounces, pounds, or stones — and every other field updates from the same figure, converted with standard international definitions rather than rounded shortcuts. The anchor value is the international avoirdupois pound, fixed by a 1959 international agreement as exactly 453.59237 grams. Every imperial unit in this tool — ounces (1/16 lb), stones (14 lb), and the pound itself — derives from that single number.

Worked example: a 75 kg adult weighs 165.35 lb or 11.81 stone; a 200 g steak is 7.05 oz; a 1000 kg shipping pallet is exactly 1 tonne, or 2204.62 lb.

What to Know

• "Pound" and "ounce" are not always the same weight. The everyday avoirdupois pound (453.59237 g) used for groceries, body weight and shipping is a different system from the troy pound (373.24 g), used historically for precious metals and still reflected today in the troy ounce. This tool converts avoirdupois units — the ones used in daily life.
• Gold and silver prices use troy ounces, not avoirdupois ounces — and the two are easy to confuse. A troy ounce is about 31.1 g, while a regular avoirdupois ounce (the one on a kitchen scale) is 28.35 g, roughly 10% lighter. Reading a metal price with the wrong ounce type produces a value that's off by that same margin.
• A "stone" is a UK/Ireland unit still used informally for body weight (14 lb per stone), rarely seen in shipping or commerce — this converter includes it because it remains common in everyday British English.
• All figures are computed at full floating-point precision and only rounded for on-screen display, so chaining several conversions doesn't compound rounding error.
• The metric side is simpler by design. Milligrams, grams, kilograms and tonnes are all powers of ten apart (1000 mg = 1 g, 1000 g = 1 kg, 1000 kg = 1 tonne), which is exactly why the metric system replaced older weight systems in most of the world — no memorized conversion factors like 16 ounces to a pound or 14 pounds to a stone.
• The kilogram itself was redefined in 2019. Until then, "1 kg" meant a specific platinum-iridium cylinder locked in a vault in France — the last SI base unit still tied to a physical object. It's now defined using the Planck constant, a fixed value from quantum physics, so mass can be reproduced anywhere with the right equipment rather than compared against one artifact.