BMI Calculator
Work out your body mass index (BMI) from your height and weight, using the standard formula (kg ÷ m²) and the WHO adult reference ranges.
BMI is a rough screening number, not a medical assessment. It can't tell muscle from fat — athletes often score “overweight” while being perfectly healthy — and the standard adult ranges don't apply to children, pregnant women or the elderly. For anything health-related, talk to a doctor; this tool is informational only.
How to calculate your BMI
- Enter your weight in kilograms.
- Enter your height in centimetres.
- Read your BMI and where it falls on the WHO adult scale.
Frequently asked questions
What formula does this use?
The standard one used worldwide: BMI = weight in kilograms ÷ (height in metres)². A 68 kg person who is 1.70 m tall has a BMI of 23.5.
What are the WHO adult ranges?
Under 18.5 is classed as underweight, 18.5–24.9 normal, 25–29.9 overweight, and 30 or above obese. These are population-level screening bands, not a diagnosis for any individual.
Why isn't BMI enough on its own?
It only relates weight to height — it can't see body composition. Muscular people score high without excess fat, and it says nothing about where fat is carried, which matters medically. A doctor looks at much more than this one number.