1. What is BMI?

Body Mass Index (BMI) is a measure of body fat based on height and weight that applies to both adult men and women. For children, BMI is age- and sex-specific and is often referred to as BMI-for-age.

2. How to Calculate BMI for Children

The calculator uses the standard BMI formula adapted for children:

Where:

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

Note: For children, BMI must be interpreted relative to other children of the same sex and age.

3. Understanding BMI Percentiles

Details: BMI percentiles show how a child's BMI compares to other children of the same age and sex:

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

4. Using the Calculator

Tips: Enter weight in kilograms, height in centimeters, and age in years (2-20 years). All values must be valid positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Why use BMI for children?
A: BMI is a reliable indicator of body fatness for most children and teens, though it doesn't measure body fat directly.

Q2: How often should my child's BMI be calculated?
A: Pediatricians typically calculate BMI at all routine checkups starting at age 2.

Q3: What if my child is very muscular?
A: BMI may overestimate body fat in athletic, muscular children. Additional assessments may be needed.

Q4: Are there limitations to BMI?
A: BMI doesn't distinguish between fat and muscle mass or account for body frame size and fat distribution.

Q5: Where can I find official growth charts?
A: The CDC provides detailed growth charts at https://www.cdc.gov/growthcharts/