1. What is BMI?

Definition: Body Mass Index (BMI) is a value derived from the mass (weight) and height of a person. The BMI is defined as the body mass divided by the square of the body height.

Purpose: BMI is a simple index of weight-for-height that is commonly used to classify underweight, normal weight, overweight and obesity in adults.

2. How Does the BMI Calculator Work?

The calculator uses the formula:

Where:

• \( BMI \) — Body Mass Index (kg/m²)
• \( W \) — Weight (kilograms)
• \( H \) — Height (meters)

Explanation: Your weight in kilograms is divided by the square of your height in meters.

3. BMI Categories (WHO Classification)

• Underweight: BMI < 18.5
• Normal weight: BMI 18.5-24.9
• Overweight: BMI 25-29.9
• Obesity Class I: BMI 30-34.9
• Obesity Class II: BMI 35-39.9
• Obesity Class III: BMI ≥ 40

4. Using the Calculator

Tips: Enter your weight in kilograms and height in meters. All values must be > 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, children, or the elderly.

Q2: What's a healthy BMI range?
A: For most adults, a healthy BMI is between 18.5 and 24.9.

Q3: How do I convert pounds to kilograms?
A: Multiply pounds by 0.453592 to get kilograms.

Q4: How do I convert feet/inches to meters?
A: First convert height to inches (feet × 12 + inches), then multiply by 0.0254 to get meters.

Q5: Does BMI measure body fat?
A: BMI is a simple screening tool but doesn't directly measure body fat percentage.