BMI Calculator
Calculate your Body Mass Index and understand what it means for your health
Your BMI Result
Enter your details to calculate your BMI
Understanding Your BMI Results
Body Mass Index (BMI) is a simple calculation using a person’s height and weight. The formula is BMI = kg/m² where kg is a person’s weight in kilograms and m² is their height in meters squared.
For adults, BMI categories are:
- Underweight: BMI less than 18.5
- Normal weight: BMI 18.5 to 24.9
- Overweight: BMI 25 to 29.9
- Obese: BMI 30 or higher
For children and teens, BMI is age- and sex-specific and is often referred to as BMI-for-age. The CDC BMI-for-age growth charts take into account these differences and allow translation of a BMI number into a percentile for a child’s sex and age.
Limitations of BMI
While BMI is a useful screening tool, it has limitations. It doesn’t directly measure body fat and doesn’t account for factors like muscle mass, bone density, or overall body composition. Athletes with high muscle mass may have a high BMI without excess fat. Older adults may have more body fat than younger adults with the same BMI.