calcolatore.online
ESIT
ITENES

Child & Adolescent BMI Calculator

Calculate your child's BMI (ages 2-18) with WHO/CDC percentiles. Check if their weight is normal for their age and sex.

Sources: CDC — BMI-for-Age Growth Charts · WHO — Child Growth Standards · American Academy of Pediatrics

How to Calculate BMI for Children and Adolescents

BMI for children and adolescents (ages 2-18) is calculated using the same formula as adults -- weight divided by height squared -- but is interpreted entirely differently, using age- and sex-specific percentiles.

Why Percentiles Are Needed

During growth, BMI naturally changes: it decreases in the first years of life, reaches a minimum around ages 5-6 (the so-called "adiposity rebound"), and then rises during puberty. A BMI of 17 is normal at age 5 but indicates underweight at age 15.

CDC Classifications

The Centers for Disease Control and Prevention (CDC) classifies pediatric BMI by percentile:

  • Underweight: below the 5th percentile
  • Normal weight: 5th to 85th percentile
  • Overweight: 85th to 95th percentile
  • Obese: above the 95th percentile

Childhood Obesity

According to WHO data, childhood obesity has become a global epidemic. Overweight and obese children face increased risks of adult obesity, type 2 diabetes, cardiovascular problems, and psychological issues. Early intervention with improved nutrition and increased physical activity is key.

When to Be Concerned

A single BMI value is less important than the trend over time. If the child's BMI crosses percentile lines upward at successive visits, consult a pediatrician. Never put a child on a restrictive diet without medical supervision.

Frequently Asked Questions

Why is BMI for children different from adults?▼
In children and adolescents, BMI naturally changes with growth. A BMI value that is normal at age 5 might indicate underweight at age 12. That's why pediatric BMI is interpreted using age- and sex-specific percentiles developed by the CDC and WHO.
What do BMI percentiles mean?▼
Percentiles indicate a child's BMI position relative to peers of the same age and sex. If a child is at the 75th percentile, their BMI is higher than 75% of children of the same age and sex. The CDC defines: below 5th = underweight, 5th-85th = normal, 85th-95th = overweight, above 95th = obese.
My child is overweight according to the calculator. What should I do?▼
The calculator provides an estimate. If the result indicates overweight or obesity, consult your pediatrician for a comprehensive evaluation that considers growth phase, puberty, muscle mass, and family history. Never put a child on a restrictive diet without medical supervision.