1. What is BMI for Kids?

Body Mass Index (BMI) is a screening tool that assesses whether a child is underweight, healthy weight, overweight, or obese. For children, BMI is age- and sex-specific and is referred to as "BMI-for-age."

2. How BMI is Calculated

The calculator uses the standard BMI formula:

Where:

• \( weight \) — Body weight in kilograms
• \( height \) — Height in meters

Note: For children, the raw BMI number is then plotted on CDC growth charts to determine the BMI percentile.

3. Understanding BMI Percentiles

Percentile ranges:

• Underweight: Less than the 5th percentile
• Healthy weight: 5th percentile to less than the 85th percentile
• Overweight: 85th to less than the 95th percentile
• Obese: Equal to or greater than the 95th percentile

4. Using the Calculator

Tips: Enter weight in kilograms, height in meters, and age in years (2-18 years). For accurate results, measure height without shoes and weight with minimal clothing.

5. Frequently Asked Questions (FAQ)

Q1: Why use BMI-for-age for children?
A: Children's body composition varies by age and sex, so BMI must be interpreted relative to other children of the same age and sex.

Q2: Is BMI accurate for all children?
A: BMI is a screening tool but doesn't directly measure body fat. Athletic children may have high BMI due to muscle mass.

Q3: How often should my child's BMI be checked?
A: The AAP recommends BMI assessment at least annually at well-child visits starting at age 2.

Q4: What if my child's BMI is high?
A: Consult your pediatrician. They may assess diet, activity level, family history, and possibly order additional tests.

Q5: Can I use this calculator for infants?
A: No, this calculator is for children ages 2-18. BMI is not recommended for infants (use weight-for-length charts instead).