1. What is BMI-for-age?

BMI-for-age is a measure that takes into account a child's age and sex when assessing their Body Mass Index. For children and teens, BMI is age- and sex-specific and is often referred to as BMI-for-age because their body composition varies as they grow.

2. How Does the Calculator Work?

The calculator uses the standard BMI formula:

Where:

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

Note: For children, this raw BMI value must be compared to age- and sex-specific growth charts to determine the BMI percentile.

3. Importance of BMI Calculation for Children

Details: BMI-for-age is the recommended measure for screening overweight and obesity in children aged 2-18 years. It helps identify children who may be at risk for weight-related health problems.

4. Using the Calculator

Tips: Enter weight in kilograms, height in meters, age in years (2-18), and select gender. All values must be valid (weight > 0, height > 0, age between 2-18).

5. Frequently Asked Questions (FAQ)

Q1: Why is BMI different for children than adults?
A: Children's body composition changes as they grow, and varies between boys and girls. BMI-for-age accounts for these normal variations.

Q2: What do the BMI percentiles mean?
A: Percentiles compare children to others of same age/sex: Underweight (<5th), Healthy weight (5th-85th), Overweight (85th-95th), Obese (≥95th).

Q3: When should BMI be measured in children?
A: The AAP recommends BMI screening annually for all children aged 2 years and older.

Q4: Are there limitations to BMI-for-age?
A: BMI doesn't distinguish between fat and muscle mass. Very muscular children may have high BMI without excess fat.

Q5: What should I do if my child's BMI is concerning?
A: Consult with a pediatrician who can perform further assessments and provide guidance on healthy growth.