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🇬🇧United Kingdom

BMI Calculator (UK)

Calculate your BMI using stones/pounds and feet/inches.

st
lb
ft
in

Results

Your BMI22.7
NHS CategoryHealthy weight
Healthy Weight Min8st 13lb
Healthy Weight Max12st 1lb
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What is BMI (UK)?

The UK BMI Calculator uses stones, pounds, feet, and inches — the units most commonly used in everyday life in Britain. BMI (Body Mass Index) is recommended by the NHS as a simple way to check whether you are a healthy weight for your height.

According to NHS data, 64% of adults in England are overweight or obese. The NHS uses BMI alongside waist circumference to assess health risks. A BMI between 18.5 and 24.9 is considered healthy by the NHS.

The NHS provides free weight management support through your GP, and the NHS Weight Loss Plan app offers a 12-week programme. If your BMI is 30+, you may be eligible for specialist weight management services through the NHS.

Note: BMI is a general guide and doesn't account for muscle mass, ethnicity, or body composition. The NHS recommends that people of Asian, Chinese, Middle Eastern, Black African, or African-Caribbean heritage use lower BMI thresholds: overweight at 23+, obese at 27.5+.

Formula

BMI = Weight (kg) / Height (m)²

Conversion: 1 stone = 14 pounds = 6.35 kg 1 foot = 12 inches = 0.3048 m

Example — 11 stone, 5'9": Weight = 11 × 6.35 = 69.85 kg Height = (5×12+9) × 0.0254 = 1.753 m BMI = 69.85 / 1.753² = 22.7 (Healthy weight)

NHS BMI Categories: - Below 18.5: Underweight - 18.5 – 24.9: Healthy weight - 25 – 29.9: Overweight - 30 – 39.9: Obese - 40+: Severely obese

Healthy weight ranges (UK units): - 5'4": 7st 11lb – 10st 5lb - 5'7": 8st 6lb – 11st 5lb - 5'9": 8st 13lb – 12st 0lb - 5'11": 9st 6lb – 12st 9lb - 6'1": 9st 13lb – 13st 5lb

How to use this BMI Calculator (UK)?

1. Enter your weight in stones and additional pounds. 2. Enter your height in feet and inches. 3. See your BMI, NHS category, and healthy weight range in stones.

If you only know your weight in kg: 1 kg = 0.157 stones. 70 kg ≈ 11 stone.

Frequently asked questions

What is a healthy BMI according to the NHS?
The NHS considers BMI 18.5-24.9 as healthy weight. However, for people of South Asian, Chinese, or Black African heritage, the NHS recommends lower thresholds: overweight starts at BMI 23 and obese at 27.5.
How accurate is BMI?
BMI is a useful screening tool but has limitations. It overestimates body fat in muscular people and may underestimate it in older people who have lost muscle mass. The NHS recommends also measuring waist circumference: men should be under 94cm, women under 80cm.
Can the NHS help with weight loss?
Yes. Your GP can refer you to NHS weight management programmes. The free NHS Weight Loss Plan app provides a 12-week programme. If your BMI is 35+ (or 30+ with health conditions), you may be eligible for specialist help including medication or surgery.
What is the average BMI in the UK?
The average BMI for adults in England is approximately 27.5 (overweight category). About 26% of adults are obese (BMI 30+) and 38% are overweight (BMI 25-29.9). Only about 35% are in the healthy weight range.
Does BMI differ for children in the UK?
Yes, the NHS uses BMI centile charts for children aged 2-18, which account for age and sex. A child is classified as overweight if above the 85th centile and obese if above the 95th centile.
How many stones should I weigh?
It depends on height. For 5'6" (168cm): healthy range is 8st 2lb to 10st 13lb. For 5'10" (178cm): 9st 3lb to 12st 5lb. For 6'0" (183cm): 9st 10lb to 13st 1lb. Use this calculator for your exact range.
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