Calculate your Body Mass Index in metric or imperial units. See your BMI category, healthy weight range for your height, and a visual scale.
| Category | BMI Range |
|---|---|
| Underweight | < 18.5 |
| Normal weight | 18.5 – 24.9 |
| Overweight | 25.0 – 29.9 |
| Obese Class I | 30.0 – 34.9 |
| Obese Class II+ | ≥ 35.0 |
Body Mass Index (BMI) is a simple numeric measure of a person's weight relative to their height. Developed by Belgian statistician Adolphe Quetelet in the 19th century, it is calculated as weight (kg) ÷ height (m)². Despite its simplicity, BMI is widely used by healthcare professionals as an initial screening tool for weight-related health conditions.
The World Health Organization defines four primary BMI categories: Underweight (BMI below 18.5), Normal weight (18.5–24.9), Overweight (25.0–29.9), and Obese (30+). Obesity is further sub-classified into Class I (30–34.9), Class II (35–39.9), and Class III (40+).
BMI does not distinguish between muscle mass and fat mass. A heavily muscled athlete may have a high BMI while having very low body fat. Conversely, a sedentary person with low muscle mass may have a "normal" BMI despite excess body fat. BMI also does not account for fat distribution — abdominal fat poses more cardiovascular risk than fat stored in the thighs.
The healthy weight range shown in this calculator is the range of weights that would produce a BMI between 18.5 and 24.9 for your specific height. This gives you a practical target range rather than a single number.