BMI Calculator in Stones & Pounds
Free UK BMI calculator — enter weight in stones-and-pounds, height in feet-and-inches. NHS-standard formula, instant result, no sign-up.
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The BMI formula in stones & feet
BMI = (weight in lbs ÷ height in inches²) × 703
Convert stones to pounds (multiply by 14) and feet to inches (multiply by 12), then apply the formula. Worked example: 11 st 2 lb = 156 lbs · 5 ft 7 in = 67 in · BMI = (156 ÷ 4,489) × 703 = 24.4.
Why the 703? It converts the imperial answer onto the same scale as the metric BMI (kg ÷ m²) so that 24.4 in stones equals 24.4 in kilograms. The healthy range of 18.5–24.9 is unit-free.
Healthy weight range in stones & pounds by height
| Height | Healthy (BMI 18.5–24.9) |
|---|---|
| 5 ft 0 | 6 st 8 lb – 8 st 12 lb |
| 5 ft 2 | 7 st 1 lb – 9 st 7 lb |
| 5 ft 4 | 7 st 8 lb – 10 st 2 lb |
| 5 ft 6 | 8 st 1 lb – 10 st 11 lb |
| 5 ft 8 | 8 st 8 lb – 11 st 6 lb |
| 5 ft 10 | 9 st 3 lb – 12 st 5 lb |
| 6 ft 0 | 9 st 11 lb – 13 st 0 lb |
| 6 ft 2 | 10 st 6 lb – 13 st 11 lb |
Rounded to nearest pound. Use the calculator above for your exact range.
Prefer kilograms? Use the metric version of this calculator.
BMI calculator (stones & pounds) — common questions
Quick answers to the most common questions
Convert your weight to pounds (1 stone = 14 lbs, so 11 st 2 lb = 156 lbs) and your height to inches (1 foot = 12 inches, so 5 ft 7 in = 67 in). Then apply the imperial BMI formula: BMI = (lbs ÷ in²) × 703. Or just use the calculator above and skip the maths.
The underlying formula is the imperial one: BMI = (weight in lbs ÷ height in inches²) × 703. Stones convert to pounds (× 14), and feet convert to inches (× 12), so a stones-and-feet input is just a friendlier wrapper over pounds-and-inches. The 703 multiplier converts the result onto the same scale as the metric kg ÷ m² formula.
One stone equals exactly 14 pounds. So 10 stone = 140 lbs, 11 stone 7 lb = 161 lbs, 12 stone 6 lb = 174 lbs. Stones are still the everyday weight unit in the UK and Ireland, while pounds are used in the US and Canada. Our calculator accepts either format and converts seamlessly.
Healthy BMI is 18.5–24.9 regardless of input units. For a 5 ft 7 in adult (170 cm) that's roughly 8 st 6 lb to 11 st 4 lb. For 5 ft 10 in (178 cm) it's 9 st 3 lb to 12 st 5 lb. For 6 ft (183 cm) it's 9 st 11 lb to 13 st 1 lb. Run the calculator with your own height to see your personal range.
It uses the identical WHO/NHS formula — weight (kg) ÷ height (m)² — and the same 18.5–24.9 healthy range. The only difference is that ours accepts UK-style stones-and-feet input directly without you needing to convert to metric first. We also have a dedicated NHS BMI calculator with NICE PH53 ethnicity-adjusted thresholds.
You don't need to convert anything — BMI is a unitless ratio, so a BMI of 24.2 is 24.2 whether you got there from kg/m² or from lbs/in². If you want to know the equivalent weight in stones, multiply pounds by 14 (or use the conversion on our result page).
Yes. The simplest approach: use our reverse BMI calculator to find your target weight at BMI 22 (the lowest-mortality point of the healthy range), then track your weight loss toward that number. A safe rate of weight loss is around 1 lb per week — roughly 1 stone every 14 weeks.
The accuracy of BMI doesn't depend on the input units — the formula is mathematically identical in stones, kilograms, or any other weight system. BMI is a screening tool for population-level risk, accurate to within ~3% as an indicator of body fat for typical adults, but less reliable for muscular athletes (where BMI overstates fat) or older adults with low muscle mass.
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