BMI formula
Metric: BMI = weight (kg) ÷ [height (m)]². Height in cm is divided by 100 first.
Imperial: BMI = 703 × weight (lb) ÷ [height (in)]².
Adult categories (WHO-style)
- Underweight: BMI < 18.5
- Normal range: 18.5–24.9
- Overweight: 25–29.9
- Obesity: BMI ≥ 30
BMI does not measure body fat directly and can misclassify athletes or older adults. Talk to a clinician for health decisions.