Calculate your Body Mass Index using the WHO standard. Supports metric (kg/cm) and imperial (lb/ft+in).
BMI isn't a perfect measure — it doesn't distinguish between muscle and fat, and it doesn't account for where weight is carried. But it's the widely used screening benchmark that GPs, insurers, and health programs rely on as a starting point.
Enter your height and weight in metric or imperial and you'll get your BMI score, the standard classification, and the healthy weight range for your height.
The standard thresholds were developed from European population data and may not be accurate for everyone. If you have any concerns about your weight, your GP can give context that no online calculator can.
18.5-24.9 is healthy for adults. Below 18.5 is underweight, 25-29.9 is overweight, 30+ is obese. These are general guidelines — individual health depends on many factors beyond one number.
No. BMI doesn't know if your weight is muscle or fat. A heavily built athlete can score overweight or obese while being in excellent health. If you strength train regularly, take the BMI result with a grain of salt.
No. Under-18s use age- and sex-specific growth chart percentiles, not fixed adult categories.
It's fast, free, and consistent — a convenient population-level screening tool even if imperfect at the individual level.
WHO classifies BMI 18.5–24.9 as healthy weight. Under 18.5 is underweight, 25–29.9 is overweight, 30+ is obese.
BMI is a useful screening tool but does not account for muscle mass, age, or ethnicity. Consult a doctor for a full health assessment.
You can switch between metric (kg, cm) and imperial (lbs, ft/in) using the toggle above.