BMI Calculator for Kids
Estimate Body Mass Index for children aged 2–19. Pediatric BMI uses age- and sex-specific percentiles for accurate interpretation.
What is BMI for Kids?
Children grow at very different rates, so the adult cut-offs (18.5, 25, 30) are not appropriate. Pediatricians use the CDC growth charts to compare a child's BMI to a reference population of the same age and sex. A child whose BMI sits at the 60th percentile is heavier than 60% of peers.
This calculator gives a simplified category for screening only. Always confirm with a paediatrician if you are concerned.
How is it calculated?
BMI = weight (kg) / height (m)². The CDC cut-offs are: < 5th percentile = underweight, 5–84th = healthy, 85–94th = overweight, ≥ 95th = obese. The simplified bands here approximate those percentiles for ages 2–19.
Frequently Asked Questions
- How accurate is a simplified pediatric BMI?
- It is a screening tool only — for clinical decisions use the official CDC charts.
- Should young children diet?
- No. Children should focus on healthy habits; weight management plans for kids must be supervised by a paediatrician.
- Why are children's BMIs so different from adults?
- Body composition changes dramatically through growth and puberty.