How to use the weight converter
- Enter the weight you want to convert in the value box.
- Pick the unit you are starting from and the unit you want to convert to.
- Press Convert to see the result immediately.
- The rate line shows how many target units equal one source unit, and the formula line shows the math that produced the answer.
How weight conversion works
This tool converts every weight through kilograms as a shared reference. Each unit has a fixed number of kilograms — a gram is 0.001 kg, a pound is 0.45359237 kg, and so on. To convert, it multiplies your value by the source unit's kilogram factor and divides by the target unit's kilogram factor. The same two steps cover tiny amounts like milligrams and large ones like tonnes.
The factors are fixed international constants, so the result is exact to the precision of your input rather than a rough estimate.
The kilogram factor of each unit
| Unit | Equals (in kilograms) |
|---|---|
| Milligram (mg) | 0.000001 kg |
| Gram (g) | 0.001 kg |
| Kilogram (kg) | 1 kg |
| Tonne (t) | 1,000 kg |
| Ounce (oz) | 0.028349523125 kg |
| Pound (lb) | 0.45359237 kg |
| Stone (st) | 6.35029318 kg |
Common weight conversions
Some everyday conversions come up often enough to be worth remembering: 1 kilogram is about 2.2 pounds, 1 ounce is just over 28 grams, and 1 stone is exactly 14 pounds. A tonne is 1,000 kilograms, while the US ton and the UK long ton differ slightly from each other, which is why this converter sticks to the internationally standard tonne. In cooking, recipes usually switch between grams and ounces, and for body weight, pounds and kilograms are the everyday pair.
Mass versus weight
Strictly speaking, mass is the amount of matter in an object, while weight is the force gravity exerts on it. The units above — grams, kilograms, pounds — are all units of mass. Because the pull of gravity is nearly constant on Earth's surface, mass and weight are used interchangeably in everyday life, and that is the everyday sense this converter uses. For scientific work that depends on local gravity, a dedicated force conversion would be needed instead.