BMI Calculator

Weight in kilograms divided by height in meters squared (kg/m²). In imperial units the equivalent is 703 × pounds ÷ inches². A 5'10" person at 165 lb works out to a BMI of about 23.7.

The conventional adult bands: under 18.5 underweight, 18.5–24.9 healthy range, 25–29.9 overweight, 30+ obese. These cutoffs come from population studies of health-outcome risk; they're screening thresholds, not diagnoses, and some populations use adjusted cutoffs.

Because it only sees mass, and muscle is denser than fat. A lean 200 lb athlete and a sedentary 200 lb person of the same height get the same BMI with very different health pictures. Waist measurement, body composition, and bloodwork tell the parts BMI can't.

Not with adult cutoffs. For ages 2–19, BMI is interpreted as an age-and-sex percentile against growth references, which is a different calculation. A pediatrician is the right interpreter for anyone still growing.