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 adjusted for children's growth patterns:

Where:

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

Explanation: The result should be interpreted using age- and sex-specific growth charts rather than adult BMI categories.

3. Importance of BMI Calculation for Kids

Details: BMI-for-age is the recommended measure for screening 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 changes as they grow, and differs between boys and girls. BMI-for-age accounts for these differences.

Q2: What do the BMI-for-age percentiles mean?
A: Percentiles compare a child's BMI to others of the same age and sex. Underweight (<5th), healthy weight (5th-85th), overweight (85th-95th), obese (≥95th).

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

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

Q5: Where can I find growth charts to interpret the results?
A: CDC growth charts are commonly used (https://www.cdc.gov/growthcharts/). Your pediatrician can help interpret results.