BMI Calculator

Body Mass Index (BMI) is a simple screening measurement that relates your weight to your height, giving a quick indication of whether you fall into an underweight, healthy weight, overweight, or obese range. It doesn't measure body fat directly, but for most adults it correlates closely enough with body fat to be useful as a fast first check.

This calculator uses the World Health Organization's standard BMI formula: weight in kilograms divided by height in meters squared (kg/m²). The WHO's classification is also what sets the category thresholds shown with your result — under 18.5 is underweight, 18.5 to 24.9 is a normal weight, 25 to 29.9 is overweight, and 30 and above is obese.

BMI is a population-level screening tool, not a diagnosis. It doesn't distinguish between muscle and fat, so a very muscular person can register as "overweight" despite having low body fat, and an older adult with reduced muscle mass can register as "normal" despite having a higher proportion of fat. It also doesn't account for where fat is distributed on the body, which matters for health risk. If your BMI falls outside the normal range, or you have concerns about your weight more broadly, talk to a doctor — they can look at the full picture, not just one number.