When you need this conversion
UK and Irish body weights on international medical or fitness forms, and fitness apps set to metric. Doctors and hospitals in the UK record weight in kilograms, even though people often talk in stone.
Quick reference
- 1 st = 6.35029 kg
- 8 st = 50.8023 kg
- 10 st = 63.5029 kg
- 12 st = 76.2035 kg
- 15 st = 95.2544 kg
Stone and pounds
Weights are often written like 11 st 4 lb. Convert to pounds first (11 × 14 + 4 = 158 lb), then to kilograms (71.6676 kg). Writing 11.4 stone is not the same thing: 0.4 stone is 5.6 lb.
Common mistakes
Reading 11.4 st as 11 st 4 lb. They differ by 1.6 lb (0.73 kg).
Using 6.35 for medical doses. It’s close enough for fitness tracking; use the exact value when a dose depends on body weight.
For the reverse, use kg to stone.