1. What is BMI?

Body Mass Index (BMI) is a simple index of weight-for-height that is commonly used to classify underweight, healthy weight, overweight and obesity in adults. The Australian Heart Foundation recommends BMI as a useful population-level measure of weight status.

2. How Does the Calculator Work?

The calculator uses the standard BMI formula:

Where:

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

Explanation: BMI provides a simple numeric measure of a person's thickness or thinness, allowing health professionals to discuss weight problems more objectively with their patients.

3. Importance of BMI Calculation

Details: BMI is an important screening tool that can indicate whether a person is underweight, at a healthy weight, overweight, or obese. Higher BMI is associated with increased risk of chronic diseases such as heart disease, high blood pressure, and type 2 diabetes.

4. Using the Calculator

Tips: Enter weight in kilograms and height in meters. For height, you can convert from cm to m by dividing by 100 (e.g., 175 cm = 1.75 m). All values must be valid (weight > 0, height > 0).

5. Frequently Asked Questions (FAQ)

Q1: What are the BMI categories according to Australian guidelines?
A: Underweight (<18.5), Healthy weight (18.5-24.9), Overweight (25-29.9), Obese (≥30).

Q2: Is BMI accurate for everyone?
A: BMI may not accurately reflect body fat in athletes (high muscle mass), elderly (loss of muscle mass), or certain ethnic groups.

Q3: Should children use this calculator?
A: No, children and teens need age- and sex-specific BMI percentiles.

Q4: What are healthy BMI ranges for older adults?
A: For those over 65, a BMI of 23-28 may be more appropriate than standard ranges.

Q5: Does BMI measure body fat?
A: BMI is a surrogate measure of body fat. For direct measurement, techniques like skinfold thickness or DXA scans are needed.