What BMI measures

Body mass index compares weight with height. The metric formula is weight in kilograms divided by height in meters squared. The US formula multiplies weight in pounds by 703, then divides by height in inches squared.

Common adult reference ranges

For adults, commonly used screening ranges are below 18.5, 18.5–24.9, 25–29.9, and 30 or higher. These labels are population-level screening categories, not a diagnosis.

Important limitations

BMI does not directly measure body fat, fitness, bone density, or fat distribution. Muscular people, older adults, pregnant people, and some ethnic groups may need different context. Adult ranges should not be used for children or teenagers.

This calculator is educational and is not medical advice. Discuss health concerns with a qualified healthcare professional.