UK BMI Calculator
Work out your Body Mass Index (BMI) in stone or kg, and see where you sit on the NHS healthy weight scale.
Last updated: 2026-08-14
Your BMI
24.1
Healthy weight
For your height, a healthy weight is between 8 st 6 lb and 11 st 5 lb (53.6–72.1 kg).
🔒Calculated in your browser. For adults only — children are measured on growth charts, not the adult BMI scale.
BMI is a rough guide to whether your weight is healthy for your height. Enter your height and weight in either stone and feet (how most people in the UK still measure themselves) or kg and cm, and this works out your number and where it falls on the NHS scale.
Frequently asked questions
How is BMI calculated?
BMI is your weight in kilograms divided by your height in metres squared. For example, 70 kg at 1.75 m tall gives 70 ÷ (1.75 × 1.75) = 22.9. If you measure in stone, multiply by 6.35 to get kg first.
What is a healthy BMI?
The NHS considers a BMI between 18.5 and 24.9 healthy for most adults. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or above is obese.
Is BMI accurate for everyone?
No. BMI does not tell muscle from fat, so muscular people can score as overweight when they are not. It is a screening tool, not a diagnosis. Athletes, older adults, and some ethnic groups should treat the number as a rough guide.