Mass Converter
Convert between metric, imperial, and US mass units instantly — kilograms, pounds, ounces, stones, tonnes, and more.
Mass converter
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From
Value
kg
Unit
Metric
Imperial / US ?
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To
Result ?
lb
Unit
Metric
Imperial / US
Other
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Precision ?
How the conversion works
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Every unit has a fixed factor against 1 kilogram, the SI base unit of mass. To convert between any two units we go through kilograms: multiply by the source factor to get kilograms, then divide by the target factor.
- mg
- milligram = 0.000001 kg (10⁻⁶)
- g
- gram = 0.001 kg (10⁻³)
- kg
- kilogram = 1 kg (base)
- t
- metric tonne = 1000 kg
- oz
- ounce (avoirdupois) = 0.028349523125 kg
- lb
- pound (avoirdupois) = 0.45359237 kg — defined exactly by the 1959 international agreement
- st
- stone = 14 lb = 6.35029318 kg
- US ton
- short ton = 2000 lb = 907.18474 kg
- UK ton
- long ton = 2240 lb = 1016.0469088 kg
- gr
- grain = 1/7000 lb = 0.00006479891 kg
Worked example — your numbers
- Input: —
- Convert to kg: —
- Convert from kg to target: —
- Result = —
Avoirdupois is the everyday system used in the UK and US for common weights. Troy and apothecaries systems (used for precious metals and pharmacology) use different pounds and ounces — this converter uses avoirdupois throughout.