1. What is BMI?

Definition: Body Mass Index (BMI) is a value derived from the mass and height of a person, providing a simple numeric measure of body fatness.

Purpose: It's used to categorize whether a person is underweight, normal weight, overweight, or obese based on tissue mass.

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.

3. BMI Categories

Details:

• Underweight: BMI < 18.5
• Normal weight: 18.5 ≤ BMI < 25
• Overweight: 25 ≤ BMI < 30
• Obese: 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: Is BMI accurate for everyone?
A: BMI is a useful screening tool but doesn't directly measure body fat. It may not be accurate for athletes (high muscle mass) or elderly (loss of muscle mass).

Q2: What's the difference between kg/m² and lb/in²?
A: The standard unit is kg/m². To calculate with pounds and inches: BMI = (weight in pounds × 703) / (height in inches)².

Q3: Why is height squared in the formula?
A: Squaring height accounts for the fact that weight increases with the square of height in most people.

Q4: Can children use this calculator?
A: Children need age- and sex-specific BMI percentiles rather than the adult categories.

Q5: What are the limitations of BMI?
A: BMI doesn't distinguish between muscle and fat, and doesn't account for fat distribution, which affects health risks.