Recipes, freight documents and bathroom scales all use different units for the same quantity, and the one that trips people up is the stone — a unit of 14 pounds that is still in everyday use in Britain and Ireland and almost nowhere else.
What the Weight Converter does
Converts between metric and imperial mass units using exact factors. A pound is exactly 0.45359237 kg, defined by the same 1959 agreement that fixed the inch.
Includes stone at 6.35029318 kg — exactly 14 pounds. Software written outside the UK routinely omits it, which is why British body-weight figures so often need converting by hand.
Open the Weight Converter and follow the settings and checks below.
Exact factors, in kilograms
| Setting | What it means |
|---|---|
| Tonne | 1000 — metric tonne, not a US ton |
| Pound | 0.45359237 — exact by definition |
| Ounce | 0.0283495231 |
| Stone | 6.35029318 — exactly 14 pounds |
| Gram | 0.001 |
| Milligram | 0.000001 |
| Default conversion | Pounds → kilograms |
| Strictly | These are units of MASS, not weight |
How to use it
- Enter the value.
- Choose the unit you have and the one you want.
- Read the result alongside every other unit.
Practical advice
Watch which ton you mean. A metric tonne is 1000 kg, a US short ton is about 907 kg, and a UK long ton about 1016 kg — a spread of over 10%. Freight paperwork that says "ton" without qualifying it is ambiguous, and the difference is real money on a shipping invoice.
Common questions
How many pounds in a stone?
Exactly 14, which is 6.35029318 kg. It survives in everyday use in Britain and Ireland for body weight and almost nowhere else, so most software omits it entirely.
Is a tonne the same as a ton?
No, and this catches people out. A tonne is metric, 1000 kg. A US short ton is 2000 lb, about 907 kg; a UK long ton is 2240 lb, about 1016 kg. Only the metric tonne is listed here, to avoid the ambiguity.
Mass or weight — does the distinction matter?
Technically these are mass units; weight is a force and varies with gravity. In everyday use the two are treated as interchangeable on Earth, and only physics and some engineering contexts need to care.
Why is a pound such an odd number of kilograms?
Because 0.45359237 was chosen in 1959 to reconcile slightly different existing US and UK pounds. It is exact by definition rather than derived — the awkwardness is the price of making both countries agree.
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Vootkit provides a browser calculator and educational guidance. Results depend on the values and units you enter, so verify important financial, academic, safety or professional decisions with an appropriate authoritative source.
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