1. What is BMI?

Body Mass Index (BMI) is a measure of body fat based on height and weight that applies to children 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, the BMI number is plotted on growth charts to determine a percentile ranking.

3. Importance of BMI Calculation for Children

Details: BMI-for-age is the most common screening tool for overweight and obesity in children aged 2-19 years. It helps identify potential weight problems that may lead to health issues.

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 by age and sex, so BMI must be compared against growth charts specific to their demographic.

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

Q3: When should BMI be measured in children?
A: The AAP recommends BMI screening annually from age 2, or more frequently if weight concerns exist.

Q4: Are there limitations to BMI for children?
A: BMI doesn't distinguish between fat and muscle mass, and may be less accurate for very muscular children or those with certain medical conditions.

Q5: What should I do if my child's BMI is high?
A: Consult with a pediatrician who can evaluate growth patterns, diet, activity level, and other health indicators.