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 a person's weight in kilograms by the square of their height in meters.

2. How Does the Calculator Work?

The calculator uses the BMI formula:

Where:

• \( weight \) — Body weight in kilograms (kg)
• \( height \) — Height in feet (ft) converted to meters by multiplying by 0.3048

Explanation: The formula converts height from feet to meters (1 foot = 0.3048 meters) before calculating the BMI value.

3. BMI Categories

Standard BMI Categories (WHO):

• Underweight: BMI < 18.5
• Normal weight: BMI 18.5-24.9
• Overweight: BMI 25-29.9
• Obesity: BMI ≥ 30

4. Using the Calculator

Tips: Enter weight in kilograms and height in feet. All values must be valid (weight > 0, height > 0).

5. Frequently Asked Questions (FAQ)

Q1: Why use BMI?
A: BMI provides a simple, standardized way to screen for weight categories that may lead to health problems.

Q2: What are the limitations of BMI?
A: BMI doesn't distinguish between muscle and fat mass, so it may misclassify muscular individuals as overweight or obese.

Q3: Is BMI different for children?
A: Yes, BMI for children is age- and sex-specific and is interpreted using percentile charts rather than fixed categories.

Q4: How accurate is BMI for different ethnic groups?
A: Some ethnic groups may have different health risks at the same BMI levels, particularly Asian populations.

Q5: Should athletes use BMI?
A: Athletes with high muscle mass may want to use additional measures like body fat percentage for more accurate assessment.