BMI Calculator
Calculate your Body Mass Index from your weight and height and see which weight category it falls into.
- Runs privately in your browser
- Free, no sign-up
- Updated
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How to use the BMI Calculator
- Enter your weight in kilograms.
- Enter your height in centimetres.
- Your BMI and weight category appear instantly.
BMI formula
BMI = weight (kg) ÷ height (m)². For example, 70 kg and 1.75 m gives 70 ÷ 3.0625 = 22.9.
BMI categories for adults
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Healthy weight |
| 25 – 29.9 | Overweight |
| 30 and above | Obesity |
These are the World Health Organization categories for adults. BMI does not measure body fat directly and doesn't account for muscle mass, age or ethnicity, so it is a screening tool rather than a diagnosis. Talk to a doctor about your health.
Frequently asked questions
Is BMI accurate for athletes?
Not always. Muscle weighs more than fat, so muscular people can have a high BMI while having low body fat.
Does this calculator work for children?
No. Children and teenagers need age- and sex-specific BMI percentiles. Use a paediatric BMI chart instead.
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