BMI Calculator
Calculate your BMI instantly. Enter height and weight, see your WHO category with assessment. Free, in your browser, no signup.
How Is BMI Calculated?
The Body Mass Index (BMI) is a measure of body weight relative to height. The formula is: BMI = weight in kg / (height in m)². A person weighing 75 kg at 1.80 m tall has a BMI of 75 / (1.80 x 1.80) = 23.1, which falls in the normal range.
BMI Categories According to WHO
The World Health Organization (WHO) classifies BMI into the following categories:
- Underweight — BMI below 18.5
- Normal weight — BMI 18.5 to 24.9
- Overweight (pre-obesity) — BMI 25.0 to 29.9
- Obesity class I — BMI 30.0 to 34.9
- Obesity class II — BMI 35.0 to 39.9
- Obesity class III — BMI 40.0 and above
Limitations of BMI
BMI does not distinguish between muscle and fat mass. A well-trained athlete may have a BMI of 28 without being overweight. For older adults, the healthy range shifts slightly upward (WHO recommends a BMI of 22–27 for those over 65). Gender, body frame, and ethnicity also affect the accuracy of BMI as a health indicator.
BMI and Health Insurance in Germany
German health insurers use BMI as an indicator for wellness programs. From a BMI of 30 (obesity), many statutory health insurers cover the costs of nutritional counseling, exercise programs, or rehabilitation measures. Some private health insurers factor BMI into premium calculations.
When Is a BMI Calculator Useful?
- Quick assessment of your weight status
- Documentation for doctor visits or nutritional counseling
- Establishing a baseline before a diet or training program
- For health insurance applications that require a current BMI