What does BMI percentile mean?
Percentage of children same sex and age with lower BMI. 60th percentile = 60% lower, 40% higher.
Health Fitness
Child BMI Calculator
Calculate child bmi with your details.
Personalized estimate
Use realistic inputs for the most useful results.
What this calculator does
Child BMI is calculated like adults but interpreted using age and sex-specific percentiles from CDC growth charts. Categories depend on percentile, not fixed numbers.
How it works
BMI = Weight(kg) ÷ Height(m)². Plot on CDC growth charts for sex and age. Categories by percentile.
Formula
Categories: Underweight <5th, Healthy 5th-85th, Overweight 85th-95th, Obese ≥95th percentile.
Tips for using this calculator
- Growth varies by age—same BMI means different things at 7 vs 13
- BMI doesn't distinguish muscle from fat in athletic children
- Track trends over time, not single measurements
- Combine with blood pressure, cholesterol, fitness
- Discuss with pediatrician for context
Frequently asked questions
My athletic child has high BMI—should I worry?
BMI doesn't distinguish muscle. Assess fitness, trajectory, and overall health with your pediatrician.
Why can't children use adult BMI categories?
Children's body composition changes during growth. Age/sex-specific percentiles account for development.