Stone to kg Calculator (st & lb → kg)
Convert a body weight given in stones — or stones and extra pounds — to kilograms, grams and total pounds using the exact international definition.
st
lb
Exact: 1 stone = 6.35029318 kg
- 1
Total pounds
11 × 14 = 154 - 2
Kilograms
154 × 0.45359237 = 69.8531 pound = 0.45359237 kg — the exact 1959 international definition.
How does this calculator work?
Multiply stones by 6.35029318 to get kilograms (1 stone = 14 lb = 6.35029318 kg). For stones-and-pounds notation, first compute total pounds (st × 14 + lb), then multiply by 0.45359237. Example: 11 st 7 lb = (154 + 7) × 0.45359237 = 73.03 kg.
Formula
How this is calculated
The stone is a unit of mass defined as exactly 14 avoirdupois pounds. Since one pound equals exactly 0.45359237 kilograms (established by the 1959 international agreement between English-speaking nations), one stone equals exactly 14 × 0.45359237 = 6.35029318 kg. This calculator multiplies your stone value by that constant — no rounding is introduced at the conversion step.
If your weight is expressed as "stones and pounds" (for example 11 st 7 lb, as commonly shown on UK bathroom scales), enter the whole-stone count in the first field and the remaining pounds in the second. The calculator converts everything to total pounds (stones × 14 + extra lbs) and then multiplies by 0.45359237.
The stone is still the dominant everyday unit for body weight in the United Kingdom and Ireland, while kilograms are standard in medicine, sport science and international contexts. Converting between the two systems is useful when comparing health-app data, medical records or fitness goals across different regions.
Frequently asked questions
One stone is exactly 6.35029318 kilograms — this follows from 1 lb = 0.45359237 kg and 1 stone = 14 lb, giving 14 × 0.45359237 = 6.35029318 kg. In everyday rounding, 1 stone ≈ 6.35 kg.
10 stone × 6.35029318 = 63.50 kg. Alternatively: 10 × 14 = 140 lb, then 140 × 0.45359237 = 63.50 kg.
UK bathroom scales and many health records display weight as "stones and pounds" (e.g. 12 st 4 lb). The extra-pounds field lets you enter that fractional part so the calculator can add it to the whole-stone total before converting — no mental arithmetic needed.
Also known as
TG we-Calculate Editorial Team. (2026). Stone to kg Calculator (st & lb → kg) [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/stone-to-kg-calculator
TG we-Calculate Editorial Team. "Stone to kg Calculator (st & lb → kg)." TG we-Calculate. 2026. https://we-calculate.com/calculator/stone-to-kg-calculator.
TG we-Calculate Editorial Team, "Stone to kg Calculator (st & lb → kg)," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/stone-to-kg-calculator
@misc{wecalculate_stone_to_kg_calculator, title = {Stone to kg Calculator (st & lb → kg)}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/stone-to-kg-calculator}}, year = {2026}, note = {TG we-Calculate} }
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