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 standard BMI formula:

Where:

• \( weight \) — Body weight in kilograms
• \( height \) — Height in meters

Explanation: BMI provides a simple numeric measure of a person's thickness or thinness, allowing health professionals to discuss weight problems more objectively with their patients.

3. Importance of BMI Calculation

Details: BMI is an inexpensive and easy screening method for weight category—underweight, healthy weight, overweight, and obesity. While BMI doesn't measure body fat directly, research has shown that BMI correlates to direct measures of body fat.

4. Using the Calculator

Tips: Enter weight in kilograms, height in meters, and optionally age in years. All values must be valid (weight > 0, height > 0). Age provides context for BMI interpretation as healthy ranges vary slightly with age.

5. Frequently Asked Questions (FAQ)

Q1: What are the BMI categories?
A: Underweight (BMI < 18.5), Normal weight (18.5-24.9), Overweight (25-29.9), and Obese (≥30).

Q2: Is BMI different for men and women?
A: The same BMI ranges apply to both men and women, though body composition differs between genders.

Q3: What are limitations of BMI?
A: BMI doesn't account for muscle mass, bone density, overall body composition, or racial and sex differences.

Q4: How does age affect BMI interpretation?
A: Older adults may have a slightly higher BMI range considered healthy compared to younger adults.

Q5: Should athletes use BMI?
A: Athletes with high muscle mass may have a high BMI that falsely suggests high body fat. Additional measures are needed.