🧒 BMI Calculator for Kids
Calculate your child’s Body Mass Index (BMI) and see a simplified weight-status estimate based on their age and sex.
Why kids’ BMI is different from adult BMI
BMI for children and teens is calculated with the exact same formula as for adults, but it is interpreted very differently, because healthy body fat levels change naturally as kids grow. Standard pediatric growth charts compare a child’s BMI to other children of the same age and sex using percentiles, rather than the fixed adult categories.
How this calculator works
This calculator computes BMI using the standard formula: weight in kilograms divided by height in meters squared. It then shows a simplified, general weight-status label based on typical pediatric BMI ranges for the given age. This is a simplified approximation and not a substitute for an official growth-chart percentile lookup from a pediatrician, which accounts for exact age in months and sex-specific growth curves.
- Official pediatric BMI assessment uses percentile charts (like the CDC or WHO growth charts), not fixed cutoff numbers.
- A single BMI reading is less meaningful for children than tracking growth trends over time.
This tool is for general educational and planning purposes only and is not a substitute for advice from a pediatrician.