Calculate Body Mass Index from height and weight. Shows WHO classification. 100% in-browser.
A free, in-browser Body Mass Index (BMI) calculator. Enter your height and weight in either metric or imperial units and see your BMI along with the World Health Organization classification. Everything runs locally in your browser — your measurements are never uploaded.
Enter your height
In metric (cm) or imperial (feet + inches). Measure without shoes, standing against a wall.
Enter your weight
In kilograms or pounds. Weigh yourself first thing in the morning for the most consistent reading.
Read your BMI
The result updates live along with the WHO category (Underweight, Normal, Overweight, Obese I/II/III).
Not always. BMI uses only height and weight, so muscular people can score in the Overweight or Obese range despite low body fat. Athletes, bodybuilders, and heavily muscled individuals should interpret BMI with caution and consider a body-fat measurement instead.
The WHO considers 18.5–24.9 kg/m² the 'normal' range for adults. Below 18.5 is underweight; 25.0–29.9 is overweight; ≥ 30 is obese. The ranges are different for children (age- and sex-specific percentiles) and are not directly applicable in pregnancy.
Either — the underlying BMI number is identical. The calculator handles the conversion internally.
No. Every calculation runs in your browser. Your height, weight, and BMI are never sent to a server.
The Body Mass Index was first described by Belgian mathematician Adolphe Quetelet in 1832 as the 'Quetelet Index' and adopted as a population-level screening tool by the WHO. The formula, weight in kilograms divided by height in metres squared, is sex- and age-agnostic for adults, which is both its strength (simple, universally applicable) and its limitation (muscle and fat are indistinguishable). The WHO cut-points at 18.5, 25, and 30 kg/m² are based on associations with cardiovascular disease and diabetes risk in large Western cohorts; cut-points for several Asian populations are lower (overweight at 23, obese at 27.5) per WHO expert consultations. Use BMI as a screen, not a diagnosis.