Weight Converter

1. 1Type a value into any box — every other unit updates as you type.
2. 2Use the swap button to flip the two headline units.
3. 3Copy any result with the button beside it.
4. 4Adjust the decimal places if you need more or less precision.

Every unit here is defined against the kilogram. The avoirdupois pound — the ordinary pound used for everyday weight — has been defined as exactly 0.45359237 kilograms since 1959, which makes ounces, stones and hundredweights exact as well.

Two traps are worth knowing about. A US ton is 2,000 pounds while a UK long ton is 2,240, and a metric tonne is 1,000 kg — three different things that all get called a ton, so they are listed separately here. Strictly, these are units of mass; weight is a force. In everyday use the distinction rarely matters, but it is why a kilogram is the same on the Moon while your weight is not.

Conversion works by taking your value to a single base unit and then out again, so every pair of units is consistent with every other. Values are calculated at full double precision and only rounded for display, which means round-tripping a number through two conversions returns what you started with.

Converting 11 stone 4 pounds to kilograms

1. 11 × 14 + 4 = 158 pounds
2. 158 × 0.45359237 = 71.67

Result: About 71.67 kilograms.