Enter your height and weight to calculate body mass index.
Body mass index (BMI) is a simple screening measure that relates weight to height, giving a quick, standardized way to flag whether a person's weight falls into an underweight, healthy, overweight, or obese range for their height. It was originally developed in the 19th century as a population-level statistical tool, not an individual diagnostic measure, but it has become the most widely used quick screening reference in clinics, insurance assessments, and general health tracking today.
BMI is useful precisely because it's simple: it only requires height and weight, no special equipment. But that simplicity is also its main limitation — it doesn't distinguish between muscle, fat, and bone density, and doesn't account for age, sex, or body frame differences. It's best used as a general screening starting point, not a full picture of health, and should be considered alongside other factors like waist circumference, body composition, and overall fitness.
Select your preferred unit system (metric or imperial), enter your weight and height, and the tool calculates your BMI along with which category it falls into. Switch unit systems at any time without needing to convert your numbers manually.
For most adults, 18.5–24.9 is generally classed as the healthy weight range, under 18.5 as underweight, 25–29.9 as overweight, and 30+ as obese.
Not always — BMI doesn't distinguish muscle from fat, so very muscular people can show a higher BMI without excess body fat, since muscle is denser than fat tissue.
Yes, switch the unit selector to use kg/cm or lb/inches, and the calculation adjusts automatically.
No — BMI ranges for children and teenagers are assessed differently, using age- and sex-specific percentile charts rather than the fixed adult categories used here, and interpretation for older adults can also differ due to natural changes in body composition with age.
BMI is a useful starting point for a general screening conversation, but it shouldn't replace a fuller assessment from a healthcare provider that considers body composition, medical history, and other individual factors.