BMI Calculator

Understanding BMI

Body Mass Index (BMI) is a simple calculation that uses height and weight to estimate whether an adult is underweight, normal weight, overweight, or obese. It is calculated by dividing weight in kilograms by height in meters squared. BMI is widely used for population-level tracking and initial screening because it is fast and requires only two measurements.

While BMI correlates reasonably well with body fat for many people, it does not directly measure body composition and can be misleading in certain cases — for example, highly trained athletes with greater muscle mass may have a higher BMI without excess body fat. Similarly, BMI does not capture fat distribution, which is an important factor for health risk.

How to use this calculator

Enter your weight (in kilograms) and your height (in centimetres). Click “Calculate” to see your BMI and a simple category such as “Underweight”, “Normal weight”, “Overweight” or “Obesity”. Use the number as a starting point for discussion with a healthcare provider if you have concerns about body composition or weight-related risk factors.

Limitations and next steps

BMI is one of many tools available. If you want a clearer picture, combine BMI with waist circumference, body fat testing, or a professional assessment. Lifestyle factors such as diet quality, physical activity, sleep and stress management also influence health beyond weight alone. If you plan to change your weight significantly, seek personalized guidance from a registered dietitian or physician.