BMI calculator
Enter your weight and height to get your BMI and its World Health Organization category.
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How it is calculated
BMI = weight (kg) / height (m)² BMI = 703 × weight (lb) / height (in)²
| BMI | WHO category |
|---|---|
| < 18.5 | Underweight |
| 18.5 – 24.9 | Healthy weight |
| 25 – 29.9 | Overweight |
| 30 – 34.9 | Obesity class I |
| 35 – 39.9 | Obesity class II |
| ≥ 40 | Obesity class III |
BMI is a population screening tool: it does not account for muscle mass, build or fat distribution. For a personal assessment, talk to a health professional.
Frequently asked questions
What is a normal BMI?
Between 18.5 and 24.9 according to the WHO.
Is BMI accurate?
It is useful as a general guide but overestimates fat in muscular people and may underestimate it in older adults.
Does it work for children?
Not directly: for under-18s BMI is interpreted with age and sex percentiles.