1. What is BMI for Children?

Body Mass Index (BMI) is a measure that adjusts body weight for height. For children and teens, BMI is age- and gender-specific and is referred to as BMI-for-age. It's used to screen for weight categories that may lead to health problems.

2. How BMI is Calculated for Kids

The calculator uses the standard BMI formula:

Where:

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

Important: For children, the BMI number is plotted on growth charts to determine the BMI-for-age percentile.

3. Understanding Percentiles

Details: Percentiles show how a child's BMI compares to other children of the same age and gender in New Zealand. For example:

• Below 5th percentile: Underweight
• 5th to 85th percentile: Healthy weight
• 85th to 95th percentile: Overweight
• Above 95th percentile: Obese

4. Using the Calculator

Tips: Enter weight in kilograms, height in meters, exact age in years (2-18), and gender. For accurate results, measurements should be taken with minimal clothing and no shoes.

5. Frequently Asked Questions (FAQ)

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

Q2: How often should my child's BMI be checked?
A: Annual checks are recommended for most children, or more frequently if weight concerns exist.

Q3: What if my child is above the 85th percentile?
A: Consult with a healthcare provider who can assess overall health, growth patterns, and provide guidance.

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

Q5: Where can I find New Zealand growth charts?
A: The New Zealand Ministry of Health provides growth charts based on WHO standards for local use.