1. What is BMI for Children?

BMI (Body Mass Index) for children is a measure that adjusts for age and sex, as children's body composition varies as they grow. Unlike adults, children's BMI is compared to growth charts to determine percentiles.

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 then be plotted on age- and sex-specific growth charts to determine the percentile.

3. Importance of BMI for Children

Details: Tracking BMI-for-age helps identify children at risk for weight-related health issues. In New Zealand, this is particularly important given childhood obesity concerns.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: What BMI percentile is considered healthy?
A: Generally, 5th to 85th percentile is healthy weight, 85th-95th is overweight, and ≥95th is obese. Underweight is <5th percentile.

Q2: Where can I find NZ growth charts?
A: The NZ Ministry of Health provides growth charts for clinical use that include BMI-for-age percentiles.

Q3: Is BMI accurate for all children?
A: BMI may not accurately reflect body fat in very muscular children or those with certain medical conditions.

Q4: How often should children's BMI be checked?
A: Annual checks are recommended as part of routine health assessments.

Q5: What's different about NZ children's BMI?
A: NZ uses growth charts that account for the country's ethnic diversity, including Māori and Pacific children who may have different growth patterns.