BMI Calculator for Children & Teens
BMI for Children (Metric)
Calculate BMI-for-age using kilograms and centimeters
kg
cm
years
BMI for Children (Imperial)
Calculate BMI-for-age using pounds, feet and inches
lbs
ft
in
years
Formula
BMI = weight (kg) / height (m)^2 | Percentile is determined by comparing BMI to CDC age- and sex-specific reference data using Z-scores: Z = (BMI - median) / SD
Frequently Asked Questions
Why is BMI calculated differently for children?
Children's body composition changes as they grow. Adult BMI categories don't apply. Instead, a child's BMI is compared to other children of the same age and sex using CDC growth charts, resulting in a percentile ranking.
What are the BMI percentile categories for children?
Underweight: below 5th percentile. Healthy weight: 5th to 84th percentile. Overweight: 85th to 94th percentile. Obese: 95th percentile or above. These are based on CDC growth charts for ages 2-19.
Is BMI accurate for children?
BMI is a useful screening tool but not diagnostic. Active, muscular children may have a high BMI without excess fat. Your pediatrician considers BMI along with growth patterns, diet, activity level, and family history.
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