Child BMI Percentile

Child BMI Percentile Calculator

Pediatric BMI runs on the same base formula as adults, BMI = weight(kg) / height(m)², but here you read the result off age- and sex-specific percentile curves instead of fixed cutoffs. A 5-year-old girl and a 12-year-old boy can share the exact same BMI number and still land in completely different nutritional categories. That's why looking it up by month of age matters.

Under the WHO Child Growth Standards (2006) and AAP/SBP, the bands work like this: below P3 is underweight, P3–P85 healthy weight, P85–P97 overweight, and above P97 obesity. Brazil’s SISVAN applies these same percentile cutoffs in primary care. Always pair the reading with the weight-for-age and height-for-age curves, since BMI on its own can be misleading in a child who is still growing.

Applications

Pediatricians, school nurses, nutritionists and parents lean on it to catch early obesity, growth faltering or feeding problems. It earns its keep in routine well-child visits, in school health programs (PSE), and when you're tracking a child with a chronic condition such as asthma, diabetes or a food allergy over time.

FAQ

Why can’t I use adult BMI cutoffs for kids? Body composition shifts a lot as kids grow; a healthy toddler carries more body fat than a 7-year-old does. Apply the fixed cutoffs (18.5/25/30) and you'd misclassify nearly every child.

What if my child is between P85 and P97? That's the overweight band and it's worth a pediatric check, but one measurement doesn't make a diagnosis. Where the growth curve is heading and what runs in the family count for more.

Is this calculator a diagnosis? No, it only screens. Before you change a child's diet, cut calories or start any kind of intervention, talk to a pediatrician or pediatric nutritionist first.