How to use
- Choose units: metric (cm, kg) or imperial (feet, inches, pounds).
- Enter height and weight — the result updates instantly.
- Read your BMI, its position on the colour scale and the normal weight range for your height.
FAQ
How is BMI calculated?
BMI = weight (kg) / height (m)². For example, at 180 cm and 75 kg: 75 / 1.8² = 23.1. Imperial height and weight are converted to metres and kilograms first.
Which categories are used?
The WHO classification for adults: below 18.5 — underweight; 18.5–24.9 — normal; 25–29.9 — overweight (pre-obesity); 30–34.9 — obesity class I; 35–39.9 — class II; 40 and above — class III.
How accurate is BMI?
It is a rough screening measure: it does not tell muscle from fat and ignores fat distribution, age and sex. Athletes with a lot of muscle can get an inflated BMI.
Is it suitable for children or during pregnancy?
No. Children and teenagers are assessed with age- and sex-specific percentile charts, and BMI based on current weight is not used during pregnancy. This calculator is for adults.
Can BMI be used for a diagnosis?
No. The result is for information only and is not medical advice. Talk to a doctor to assess your health and weight.