BMI Calculator
Calculate your Body Mass Index from height and weight. Get health category and recommendations. Free, instant, no signup.
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Frequently asked questions
- What BMI range is considered healthy?
- Adults: 18.5-24.9 is normal weight. Below 18.5 is underweight, 25-29.9 is overweight, 30+ is obese. BMI alone is not a full health assessment.
- Does BMI work for athletes?
- Not well. Muscle weighs more than fat, so athletes often show high BMI despite being fit. Use body fat percentage instead.
- Does BMI work for children?
- Use pediatric BMI percentiles, not the adult formula. This tool is designed for adults 18+.
- Metric or imperial?
- Both. Toggle between kg/cm (metric) and lb/ft (imperial) - the result is always calculated correctly.
- How is the healthy weight range worked out?
- It is the weight band that puts your BMI between 18.5 and 24.9 at the height you entered, so a taller person gets a wider band.
- Does age or sex change the result?
- No. The formula uses only weight in kilograms divided by height in metres squared. Age, sex, and ethnicity do affect how the number should be read, which is why the category is a screening hint rather than a diagnosis.