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 a person's weight in kilograms divided by the square of their height in meters (kg/m²).

2. How Does the Calculator Work?

The calculator uses the BMI formula:

Where:

• \( weight \) — Body weight in kilograms (kg)
• \( height \) — Height in meters (m), converted from centimeters (cm)

Explanation: The formula calculates body mass per unit of height squared, providing a standardized measure for comparing body weights across different heights.

3. BMI Categories

Standard BMI Categories:

• 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 centimeters. All values must be valid (weight > 0, height > 0).

5. Frequently Asked Questions (FAQ)

Q1: Is BMI accurate for everyone?
A: BMI may not accurately reflect body fat in athletes (who may have high muscle mass), the elderly, or those with different body compositions.

Q2: What are the limitations of BMI?
A: BMI doesn't distinguish between muscle and fat mass, and doesn't account for fat distribution which affects health risks.

Q3: Should children use this calculator?
A: Children and teens need age- and sex-specific BMI percentiles rather than adult categories.

Q4: How often should I check my BMI?
A: For most adults, checking every few months is sufficient unless you're actively trying to change your weight.

Q5: What's a healthy BMI range?
A: For most adults, 18.5 to 24.9 is considered healthy, but individual health factors should also be considered.