Weight & mass converter
Convert kilograms, pounds, grams, ounces, stones and tonnes. Exact conversion factors, the working shown, and the three tons kept apart.
Common weight conversions
Not sure which unit you need?
Read the weight unit guide — what each one is, where it came from, and which of them are quietly different from each other.
Every weight unit
| Unit | Symbol | In kilograms |
|---|---|---|
| Milligrams | mg | 0.000001 |
| Grams | g | 0.001 |
| Kilograms | kg | 1 |
| Tonnes | t | 1,000 |
| Grains | grain | 0.00006479891 |
| Carats | ct | 0.0002 |
| Ounces | oz | 0.02834952 |
| Pounds | lb | 0.45359237 |
| Stone | st | 6.350293 |
| Short tons | short ton | 907.18474 |
| Long tons | long ton | 1,016.05 |
Questions
Is a ton the same everywhere?
No, and the gap is wide enough to matter on an invoice. A tonne is 1,000 kg. A US short ton is 907.18474 kg. A UK long ton is 1,016.0469088 kg. Shipping quotes that say only "ton" are worth querying.
What is the difference between weight and mass?
Mass is how much matter something contains and does not change. Weight is the force gravity applies to that mass, so it changes with location. Everyday use treats them as one thing, and every unit on this page is really a unit of mass.
Why is the pound exactly 0.45359237 kilograms?
Because the countries still using the pound agreed in 1959 to define it against the kilogram rather than maintain a separate physical standard. The figure is a definition, so it never rounds and never drifts.
How do I read weight in stone and pounds?
One stone is 14 pounds. British body weight is usually given as stone plus a remainder, so 11 st 4 lb means 158 pounds, or about 71.7 kg.