1. What is BMI?

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

2. How Does the Calculator Work?

The calculator uses the BMI formula:

Where:

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

Note: For children and teens, the BMI number is plotted on the CDC BMI-for-age growth charts to determine the corresponding BMI-for-age percentile.

3. Importance of BMI Calculation for Children

Details: BMI-for-age is the most widely used indicator to screen for weight categories that may lead to health problems in children and teens. It helps identify potential weight problems that might otherwise be missed by height and weight measurements alone.

4. Using the Calculator

Tips: Enter weight in kilograms, height in meters, age in years (2-19), and select gender. All values must be valid (weight > 0, height > 0, age between 2-19).

5. Frequently Asked Questions (FAQ)

Q1: Why is BMI different for children than adults?
A: Children's body composition varies as they grow, so BMI must be considered relative to other children of the same age and sex.

Q2: What do the BMI percentiles mean?
A: Underweight (<5th percentile), Healthy weight (5th-85th percentile), Overweight (85th-95th percentile), Obese (≥95th percentile).

Q3: When should I be concerned about my child's BMI?
A: Consult a healthcare provider if your child's BMI is below the 5th percentile or above the 85th percentile.

Q4: Are there limitations to BMI for children?
A: BMI doesn't distinguish between fat and muscle mass, so athletic children may have a high BMI without excess fat.

Q5: How often should children's BMI be measured?
A: The American Academy of Pediatrics recommends BMI screening annually from age 2.