BMI Calculator
Calculate Body Mass Index from height and weight, metric or imperial.
Last updated August 26, 2026
22.9
Healthy weight
About this tool
Body Mass Index (BMI) is a simple screening measure calculated from height and weight, used by health organizations worldwide as a quick (though imperfect) indicator of whether someone's weight falls in a typical range for their height. This tool calculates BMI from either metric (cm/kg) or imperial (ft/in/lb) inputs and classifies the result according to the standard WHO categories.
WHO BMI categories (adults)
| BMI range | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5–24.9 | Healthy weight |
| 25–29.9 | Overweight |
| 30 and above | Obesity |
Frequently asked questions
Is BMI an accurate measure of health for everyone?
No — BMI doesn't distinguish muscle mass from fat mass, so athletes and very muscular individuals often score as “overweight” despite low body fat. It's a population-level screening tool, not a precise individual health diagnosis, and shouldn't replace advice from a healthcare provider.
What formula is used to calculate BMI?
Metric: weight (kg) ÷ height (m)². Imperial: 703 × weight (lb) ÷ height (in)² — the 703 factor makes the imperial formula produce the same result as the metric one.
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