Child BMI Calculator & Percentile Guide
Updated 19 September 2026 · MetaSys Limited · Educational information
This tool calculates BMI only. It does not assign a percentile or weight category.
Child and teen BMI interpretation requires age- and sex-specific growth references. For a percentile, use the official CDC calculator for ages 2 through 19 and discuss the result with your child’s clinician. This page is intended for parents and caregivers.
What is BMI?
BMI is weight in kilograms divided by height in meters squared. For example, 32 kg at 1.35 m gives 32 ÷ 1.35² = 17.6 kg/m² after rounding. For a child, that number has no stand-alone adult-style category.
Why no percentile here?
The previous implementation used a simplified, invented reference curve. We removed it because it could assign misleading categories. The CDC tool uses age- and sex-specific reference data. A clinician also considers the child’s growth over time and clinical context.
Does a high BMI diagnose a health problem?
No. BMI is a screening measure, not a diagnosis, and does not directly measure body fat. Do not start a child on a diet based on this number. See CDC’s explanation of child BMI categories.