Stone to Kilograms
Convert stone to kilograms instantly. Free, fast, no signup.
How to use this tool
- Enter stone in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your kilograms and the full breakdown beneath it.
Convert stone to kilograms instantly. Free, fast, no signup.
Formula
Kilograms = Stone × 6.35029318
One stone = 14 lb, and 14 × 0.45359237 kg/lb = 6.35029318 kg exactly.
How it works
Multiply the number of stone by 6.35029318 to obtain kilograms. The stone is not part of the metric system but is defined precisely through the pound, making the conversion factor exact. This unit is common for body weight in the United Kingdom and Ireland but is rarely used elsewhere.
Common mistake: Confusing the input by mixing stone and pounds — entering just the stone count when the actual weight is expressed as, for example, '11 st 4 lb'. To convert a mixed stone-and-pounds value, first convert the pounds to a decimal fraction of a stone (divide by 14) and add it to the whole stones before multiplying by 6.35029318.
Worked example
Convert 1 stone to kilograms
- Start with 1 stone.
- Multiply by the exact conversion factor: 1 × 6.35029318.
- Round to four decimal places: 6.3503 kg.
1 stone = 6.3503 kilograms
Common mistakes to avoid
- Using 6.3 instead of the exact 6.35029318 per stone, understating each stone by about 50 g -- over 10 stone that is half a kilogram of error.
- Entering only the stone part and omitting the pounds -- 11 st 4 lb must be converted to 11.286 st (4 / 14 = 0.286) before multiplying.
- Dividing by 6.35 instead of multiplying -- that converts kg to stone.
Key terms
- Stone (st)
- A traditional British unit of mass equal to 14 avoirdupois pounds or exactly 6.35029318 kg.
- Kilogram (kg)
- The international standard unit of mass, used globally in science, medicine, and most countries' everyday life.
- Mixed stone-pounds notation
- Body weight often written as 'X st Y lb' where Y is an additional whole pounds on top of the stone value; convert Y to stone by dividing by 14 before applying the multiplier.
- Exact definition
- Because the pound is defined as exactly 0.45359237 kg and a stone is exactly 14 lb, 1 st = 6.35029318 kg carries no measurement uncertainty.
Frequently asked questions
- How do I convert stone to kilograms?
- Multiply the number of stone by 6.35029 to get kilograms.