Enter your height and weight to calculate your body mass index instantly. The calculation runs in your browser; nothing you enter is sent anywhere or stored.
The height and weight you enter are used only in your browser. They are not sent to a server, not stored and not shared with third parties.
| Class | BMI range |
|---|---|
| Underweight | below 18.5 |
| Normal | 18.5 - 24.9 |
| Overweight | 25.0 - 29.9 |
| Obesity class I | 30.0 - 34.9 |
| Obesity class II | 35.0 - 39.9 |
| Obesity class III | 40.0 and above |
Body mass index is weight divided by the square of height, and it sums up weight status in a single number. It is a quick screening tool at population level, but it is not a diagnosis for any individual.
BMI does not distinguish muscle from fat. It can therefore read high in athletes with substantial muscle mass and low in older people who have lost muscle. Nor does it show how fat is distributed, yet fat carried around the waist carries a higher risk than fat around the hips. Separate criteria apply in children and in pregnancy.
For these reasons BMI is assessed alongside waist circumference, blood glucose, blood lipids, blood pressure and overall health rather than on its own.
The internationally accepted criteria are:
These numbers do not make the decision; they only open the assessment. Age, eating habits, previous weight-loss attempts, psychological readiness and general health are weighed together. Which method suits you can only be determined after examination and the necessary investigations.
Weight in kilograms is divided by height in metres squared. For someone 1.70 m tall weighing 85 kg: 85 / (1.70 x 1.70) = 29.4.
No. A BMI between 30 and 35 is not on its own an indication for surgery. In this range, diet, physical activity and, where appropriate, medical treatment are considered first.
BMI does not distinguish muscle from fat. It can read high in people with substantial muscle mass without any excess fat. Body fat percentage is more informative in that situation.
Fat carried around the abdomen carries a higher risk of heart disease and type 2 diabetes than fat around the hips and legs. Waist circumference therefore complements BMI.
Disclaimer. This page is provided for general information only. Body mass index is a screening tool; it does not constitute a medical diagnosis, advice or a treatment recommendation, and it is not a substitute for examination by a physician. Whatever your result, discuss decisions about your health with your own doctor.