Weight Converter

How it is calculated

Every unit is defined by a fixed factor to the kilogram: base_kg = value × factor_from, then result = base_kg ÷ factor_to. The factors used are 1 lb = 0.45359237 kg, 1 oz = 0.028349523125 kg, 1 st = 6.35029318 kg, 1 t = 1000 kg, 1 g = 0.001 kg and 1 mg = 0.000001 kg. The value is the amount in the unit you choose under from; if that unit is not recognised the tool falls back to kilograms. All seven units are shown at once, each rounded to two decimals, so very small results (a few grams expressed in tonnes) can show as 0.00.

Common mistakes

• Leaving the from unit on kilograms while typing a pound value, which makes the answer roughly 2.2 times too large.
• Confusing the tonne (t, 1000 kg) with the imperial ton; this tool only uses the metric tonne.
• Reading stone as a decimal: 10.71 st is 10 stone and about 10 lb (0.71 × 14), not 10 stone 71 lb.
• Trusting the rounded figure for further maths; tiny values in tonnes are rounded to two decimals, so convert from grams or kilograms instead.
• Mixing up ounces of weight (oz) with fluid ounces of volume; they are not interchangeable.