BMI for Children — Important Note

BMI for children is calculated the same way as adults, but interpretation is completely different. Children's body composition changes rapidly with age and gender. A pediatrician must interpret BMI using age-and-gender-specific growth charts (percentiles).

Why Adult BMI Categories Don't Apply to Kids

An adult BMI of 18 is "normal" but for a 5-year-old, it may be "underweight". Children's BMI is compared against other children of the same age and gender using CDC or WHO growth charts.

BMI Categories for Children (Percentile-Based)

• Below 5th percentile: Underweight
• 5th to 85th percentile: Healthy weight
• 85th to 95th percentile: Overweight
• Above 95th percentile: Obese

BMI Formula (Same as Adults)

BMI = Weight (kg) ÷ Height (m)²

What Affects a Child's BMI?

• Age and gender
• Growth spurts
• Muscle mass (athletic kids may show higher BMI)
• Genetic factors
• Diet and physical activity

When to Consult a Pediatrician

• BMI is below 5th percentile (underweight)
• BMI is above 85th percentile (overweight)
• Sudden weight gain or loss
• Eating or activity concerns
• Any persistent health issue

Healthy Habits for Kids

• Balanced diet with fruits and vegetables
• At least 60 minutes of physical activity daily
• Limited screen time (max 2 hours/day)
• 8-11 hours of sleep depending on age
• Regular health checkups

Why Use Our Calculator?

Quick BMI number for your child. But remember — only a pediatrician can properly interpret it using growth charts. Always consult a doctor.