Conversion examples
Same body, three unit systems. The BMI value is identical regardless of the units you use.
| Metric | Imperial | Stones | BMI | Category |
|---|---|---|---|---|
| 60 kg, 165 cm | 132 lbs, 5'5" | 9 st 6 lbs, 5'5" | 22.0 | Healthy weight |
| 76 kg, 178 cm | 168 lbs, 5'10" | 12 st 0 lbs, 5'10" | 24.0 | Healthy weight |
| 89 kg, 178 cm | 196 lbs, 5'10" | 14 st 0 lbs, 5'10" | 28.1 | Overweight |
| 102 kg, 178 cm | 224 lbs, 5'10" | 16 st 0 lbs, 5'10" | 32.2 | Obese |
Common mistakes
- Confusing stones with pounds: 1 stone = 14 lbs
- Entering '12.5 st' meaning 12 stones 7 lbs — should be entered as 12 st 7 lbs
- Mixing stones with kg
Frequently asked questions
What is a healthy BMI according to the NHS?
NHS uses the same WHO standards: 18.5–24.9 is healthy weight, 25–29.9 is overweight, 30+ is obese. Below 18.5 is underweight.
How do I convert stones to kilograms?
1 stone = 6.35 kg. So 12 stones = 76.2 kg, 14 stones = 88.9 kg. To convert: stones × 6.35 = kg.
What is 'BMI prime'?
BMI prime is your BMI divided by 25 (the upper limit of healthy range). A BMI prime of 1.0 means you're at the upper edge; below 1.0 is healthy. Less commonly used than standard BMI.
Does the NHS use Asian-adjusted BMI cutoffs?
Yes, since 2017. NHS recognises that South Asian, Chinese, and other Asian populations have increased health risk at lower BMI. NHS guidance: overweight starts at BMI 23 for these groups.
Where can I get NHS support for weight loss?
Free NHS support includes the NHS Weight Loss Plan (12-week app), referrals from your GP, and local programmes via your CCG. Visit nhs.uk/live-well/healthy-weight for resources.
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