1. What is BMI?

Body Mass Index (BMI) is a simple index of weight-for-height that is commonly used to classify underweight, normal weight, overweight and obesity in adults. It is calculated by dividing weight in kilograms by height in meters squared.

2. How Does the Calculator Work?

The calculator uses the standard BMI formula:

Where:

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

Interpretation: According to NZ Heart Foundation guidelines:

• Underweight: BMI < 18.5 kg/m²
• Normal weight: BMI 18.5-24.9 kg/m²
• Overweight: BMI 25-29.9 kg/m²
• Obese: BMI ≥ 30 kg/m²

3. Importance of BMI Calculation

Details: BMI provides a simple numeric measure of body fatness for most people and is used to screen for weight categories that may lead to health problems.

4. Using the Calculator

Tips: Enter weight in kilograms and height in meters. For accurate results, measure weight in light clothing and height without shoes.

5. Frequently Asked Questions (FAQ)

Q1: Is BMI accurate for everyone?
A: BMI may not accurately reflect body fatness in athletes (who have high muscle mass), the elderly, or those with unusual body proportions.

Q2: What are the health risks associated with high BMI?
A: Higher BMI is associated with increased risk of heart disease, stroke, type 2 diabetes, and certain cancers.

Q3: How often should I check my BMI?
A: Adults should monitor their BMI annually, or more frequently if actively trying to lose or gain weight.

Q4: Are there different BMI categories for different ethnic groups?
A: Some populations (e.g., Asian, Pacific) may have different health risks at lower BMI thresholds.

Q5: Should children use this calculator?
A: No, children and teens need age- and sex-specific BMI percentiles rather than adult categories.