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 defined as the weight in kilograms divided by the square of the height in meters (kg/m²).

2. How Does the Calculator Work?

The calculator uses the standard BMI formula:

Where:

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

Interpretation: The result is compared against standard BMI categories:

• 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 a person's thickness or thinness, allowing health professionals to discuss weight problems more objectively with their patients. It 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 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: Is BMI accurate for everyone?
A: BMI may not be accurate for athletes (who may have high muscle mass), pregnant women, the elderly, or children. Other measurements may be needed.

Q2: What is a healthy BMI range?
A: For most adults, a healthy range is 18.5 to 24.9 kg/m², though this may vary by ethnicity and other factors.

Q3: How often should I check my BMI?
A: For most adults, checking every 6-12 months is sufficient unless you're actively trying to change your weight.

Q4: Does BMI measure body fat?
A: BMI is a surrogate measure of body fat for most people, but it doesn't directly measure body fat percentage.

Q5: Are there different BMI standards for South Africa?
A: While the standard categories are used, some research suggests lower BMI cut-offs may be appropriate for certain ethnic groups in South Africa.