1. What is BMI?

BMI (Body Mass Index) is a measure that uses height and weight to estimate body fat. 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:

• \( weight \) — Weight in kilograms (kg)
• \( height \) — Height in meters (m)

For children and teens: The calculated BMI is compared against age- and sex-specific percentiles from New Zealand growth charts.

3. Importance of BMI Calculation

Details: BMI is a screening tool that can indicate whether a child is underweight, healthy weight, overweight, or obese. It helps identify potential weight problems that may lead to health issues.

4. Using the Calculator

Tips: Enter weight in kg, height in meters, age in years, and select gender. For accurate results, measurements should be taken with minimal clothing and no shoes.

5. Frequently Asked Questions (FAQ)

Q1: Is BMI accurate for children?
A: BMI-for-age is the recommended screening measure for children, but it's not a diagnostic tool. A healthcare provider should evaluate any concerns.

Q2: What are the BMI categories for children?
A: In NZ, children are classified as underweight (<5th percentile), healthy weight (5th-85th), overweight (85th-95th), or obese (≥95th percentile).

Q3: When should BMI be measured?
A: Regular BMI measurements are recommended as part of routine child health checks in New Zealand.

Q4: Are there limitations to BMI?
A: BMI doesn't distinguish between muscle and fat, and may not be accurate for very muscular children or those with certain medical conditions.

Q5: Where can I find NZ growth charts?
A: The New Zealand Ministry of Health provides growth charts that include BMI-for-age percentiles.