About this tool
Calculates Body Mass Index from weight and height, in metric (kg/cm) or imperial (lb/in) units. Shows the numeric value and the corresponding category according to the World Health Organization classification: underweight, normal weight, overweight, obesity.
How to use
- Pick the unit system (metric or imperial).
- Enter weight and height in the corresponding fields.
- Read the calculated value and the matching category.
Frequently asked questions
- Is BMI a reliable measure of health?
- It's useful but limited. It doesn't distinguish muscle from fat, doesn't account for body distribution or ethnic composition. Athletes with a lot of muscle mass can have high BMI without excess fat. Elderly people with little muscle mass can have normal BMI yet concerning body composition. Treat the result as indicative, not as a diagnosis.
- What classifications are used?
- Those of the World Health Organization for adults: below 18.5 (underweight), 18.5 to 24.9 (normal weight), 25 to 29.9 (overweight), 30 to 34.9 (obesity class I), 35 to 39.9 (obesity class II), above 40 (obesity class III).
- Does it apply to children and adolescents?
- No. For under 18s, BMI is interpreted using age and sex-specific percentiles, not the adult categories. This tool calculates the numeric value but the categories shown only make sense for adults.