BMI Calculator
Work out your body mass index from your height and weight.
- BMI
- –
- Band
- –
Adult BMI bands
- Underweight
- Below 18.5
- Normal weight
- 18.5 to 24.9
- Overweight
- 25 to 29.9
- Obese
- 30 and above
Bands from the World Health Organization (Technical Report Series 894, 2000), checked against its fact sheet "Obesity and overweight" of 7 October 2026. The bands are for adults.
How to work out your BMI
- Choose the units for your height and your weight.
- Type your height and your weight.
- Read your BMI and its band as you type.
Questions
How is BMI worked out?
It is your weight in kilograms divided by the square of your height in metres. Feet, inches, pounds and stones are converted to metric first.
Where do the bands come from?
From the World Health Organization's classification for adults. Below 18.5 is underweight, 18.5 to 24.9 normal weight, 25 to 29.9 overweight, and 30 and above obese.
Does it work for children?
No. The bands are for adults. Children's BMI is read against growth charts for their age and sex, which this calculator does not use.
Is this medical advice?
No. It shows the number for the height and weight you enter, and its band. Talk to a doctor about what it means for you.
Is anything I enter sent anywhere?
No. Every calculation happens inside your browser, and nothing is saved.