Stones, pounds and BMI
Many people in the UK know their weight in stones and pounds but their height in feet and inches. Choose UK units and enter both directly — the calculator converts 1 stone to 14 lb (6.35 kg) and shows your healthy weight range back in stones and pounds.
Children in the UK
For children, UK services use centile charts rather than adult ranges. The Child BMI Calculator gives a BMI-for-age percentile based on the CDC reference, which is close to the UK90 charts used in the National Child Measurement Programme.
Adult BMI categories
From the age of 20, everyone uses the same World Health Organization categories, whatever their sex or age:
| BMI (kg/m²) | Adult category (WHO) |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Healthy weight |
| 25.0 – 29.9 | Overweight |
| 30.0 – 34.9 | Obesity class I |
| 35.0 – 39.9 | Obesity class II |
| 40 or more | Obesity class III |
Waist-to-height ratio
UK guidance recommends measuring waist as well as BMI for adults with a BMI under 35. Keep your waist to less than half your height: a ratio of 0.5 to 0.59 means increased risk, and 0.6 or more high risk. At 5 ft 6 in (168 cm), half your height is 84 cm (33 in).
Healthy weight in stones and pounds
For readers who weigh themselves in stones — the healthy BMI range of 18.5 to 24.9 at common heights:
| Height | Healthy weight (BMI 18.5–24.9) | BMI 30 (obesity) from |
|---|---|---|
| 4 ft 10 in | 6 st 5 lb – 8 st 7 lb | 10 st 4 lb |
| 5 ft 0 in | 6 st 11 lb – 9 st 1 lb | 11 st 0 lb |
| 5 ft 2 in | 7 st 3 lb – 9 st 10 lb | 11 st 10 lb |
| 5 ft 4 in | 7 st 10 lb – 10 st 5 lb | 12 st 7 lb |
| 5 ft 6 in | 8 st 3 lb – 11 st 0 lb | 13 st 4 lb |
| 5 ft 8 in | 8 st 10 lb – 11 st 10 lb | 14 st 1 lb |
| 5 ft 10 in | 9 st 3 lb – 12 st 6 lb | 14 st 13 lb |
| 6 ft 0 in | 9 st 10 lb – 13 st 2 lb | 15 st 11 lb |
| 6 ft 2 in | 10 st 4 lb – 13 st 12 lb | 16 st 10 lb |
| 6 ft 4 in | 10 st 12 lb – 14 st 9 lb | 17 st 8 lb |