1. What is BMI Calculator on MDCalc?

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, 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: The weight in kilograms is divided by the square of height in meters to calculate BMI.

3. BMI Categories

Details:

• 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 your weight in kilograms and height in meters. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is BMI important?
A: BMI provides a simple numeric measure of a person's thickness or thinness, allowing health professionals to discuss weight problems objectively.

Q2: Is BMI accurate for everyone?
A: BMI may not be accurate for athletes (muscle weighs more than fat), pregnant women, children, or the elderly. It's a screening tool, not a diagnostic.

Q3: How do I convert pounds to kilograms?
A: 1 pound = 0.453592 kg. Multiply pounds by 0.453592 to get kilograms.

Q4: How do I convert feet/inches to meters?
A: 1 foot = 0.3048 meters. 1 inch = 0.0254 meters. Multiply feet by 0.3048 and inches by 0.0254, then add them together.

Q5: What's a healthy BMI range?
A: For most adults, a healthy BMI is between 18.5 and 24.9.