Why is child BMI shown as a percentile instead of a number?

Children's body composition changes with age and differs by sex, so a raw BMI is not meaningful on its own. The BMI-for-age percentile compares a child to others of the same age and sex using CDC reference data.

What do the categories mean?

CDC defines below the 5th percentile as underweight, 5th to under 85th as a healthy weight, 85th to under 95th as overweight, and 95th percentile or above as obesity.

Is this suitable for adults?

No. This calculator uses pediatric reference data for ages 2 to 20. Adults should use a standard BMI calculator instead.

BMI-for-Age Percentile Calculator

BMI-for-age percentile calculator

Enter a child’s sex, age, height and weight to calculate their BMI, BMI-for-age percentile and CDC weight category. The percentile compares the child to others of the same age and sex.

This tool uses the CDC 2000 growth-chart LMS parameters (ages 2–20) and the standard normal distribution to convert BMI into a percentile. It is an estimate for general guidance, not a diagnosis — discuss any concerns with a pediatrician. All calculation runs privately in your browser.