1. What is BMI?

Body Mass Index (BMI) is a measure that uses height and weight to work out if a person's weight is healthy. 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 standard BMI formula:

Where:

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

Note: For children, the BMI value is plotted on 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 potential weight problems that may lead to health issues.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: How is child BMI different from adult BMI?
A: Child BMI is interpreted relative to other children of the same age and sex, using percentile charts rather than fixed categories.

Q2: What are the BMI percentile categories for children?
A: Underweight (<5th), Healthy weight (5th-<85th), Overweight (85th-<95th), 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 at/above the 85th percentile.

Q4: Are there limitations to BMI for children?
A: BMI doesn't distinguish between fat and muscle mass. Athletic children may have high BMI due to muscle rather than fat.

Q5: Where can I find Australian BMI growth charts?
A: The Australian Government Department of Health provides BMI-for-age growth charts based on WHO standards.