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Body Mass Index in either unit system: centimetres and kilograms, or feet, inches and pounds. You get the BMI value, its category under the WHO classification (underweight, healthy, overweight, obesity), and — more useful — the actual weight range that corresponds to the healthy band for your height.
BMI is a population screening measure, not a verdict: it can't distinguish muscle from fat, so athletes often read "overweight" while perfectly lean. Treat it as one signal among several.
Frequently asked questions
What's a healthy BMI?
The WHO healthy range is 18.5–24.9. Below 18.5 is classed underweight, 25–29.9 overweight, 30+ obesity. The calculator shows what that range means in actual kilograms or pounds for your height.
How is BMI calculated?
Weight in kilograms divided by height in metres squared (kg/m²). Imperial inputs are converted first — the formula itself is always metric.
Why does BMI mislabel muscular people?
It only knows mass and height. Muscle is denser than fat, so muscular builds score high without excess fat. Waist measurements or the body fat calculator give a more complete picture.