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Weight conversion turns on which pound you mean. The avoirdupois pound, 0.45359237 kg, is the one on grocery shelves and bathroom scales; the troy pound used for precious metals is about 21% heavier. Every converter on this site uses avoirdupois.
Three conversions cause most of the confusion. One kilogram is 2.20462 pounds. One stone is 14 pounds, which is why British body weight is often quoted in stones and pounds. And one US ton is 2,000 pounds (907.18474 kg) while one metric tonne is 1,000 kg (2,204.62 lb) - the same word, roughly 9% apart in value, with the UK's old long ton of 2,240 lb a third reading on top of that.
| mg | g | kg | oz | lb | st | ton | |
|---|---|---|---|---|---|---|---|
| 1 mg | 1 | 0.001 | 1.0000e-06 | 3.5274e-05 | 2.2046e-06 | 1.5747e-07 | 1.1023e-09 |
| 1 g | 1000 | 1 | 0.001 | 0.035274 | 0.002205 | 0.000157 | 1.1023e-06 |
| 1 kg | 1.0000e+06 | 1000 | 1 | 35.273962 | 2.204623 | 0.157473 | 0.001102 |
| 1 oz | 28349.523125 | 28.349523 | 0.02835 | 1 | 0.0625 | 0.004464 | 3.1250e-05 |
| 1 lb | 453592.37 | 453.59237 | 0.453592 | 16 | 1 | 0.071429 | 0.0005 |
| 1 st | 6.3503e+06 | 6350.29318 | 6.350293 | 224 | 14 | 1 | 0.007 |
| 1 ton | 9.0718e+08 | 907184.74 | 907.18474 | 32000 | 2000 | 142.857143 | 1 |
How many pounds are in a kilogram? 2.20462. Going the other way, one pound is 0.45359237 kg, so 150 lb is about 68 kg. A quick mental method is to halve the kilograms and add 10%.
What is a stone? 14 pounds, used mainly in the UK and Ireland for body weight. Someone who weighs 11 stone is 154 lb, or about 70 kg.
Is a US ton the same as a metric tonne? No - it is about 9% lighter. A US short ton is 2,000 lb, or 907.18474 kg, while a metric tonne is 1,000 kg, or 2,204.62 lb. The old UK long ton was 2,240 lb, which is why the bare word ton is ambiguous.
Why is the ounce used for both weight and volume? The fluid ounce measures volume and the ounce measures weight, and they coincide only for water. A fluid ounce of honey weighs about 1.4 ounces, so liquids belong in the volume converters.