1. What is Body Mass Index (BMI)?

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 BMI 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, normal weight, overweight, and obesity. It correlates moderately well with direct measures of body fatness.

4. Using the Calculator

Tips: Enter weight in kilograms, height in meters, and optionally age. All values must be valid (weight > 0, height > 0). For most accurate results, measure weight and height without shoes and heavy clothing.

5. Frequently Asked Questions (FAQ)

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

Q2: Does BMI interpretation change with age?
A: For adults, the same categories apply regardless of age. However, BMI naturally increases with age until middle age then decreases slightly.

Q3: What are BMI limitations?
A: BMI doesn't distinguish between muscle and fat mass, so athletes may have high BMI without excess fat. It also doesn't account for fat distribution.

Q4: Is BMI different for children?
A: Yes, children's BMI is age and sex-specific and interpreted using percentile charts rather than fixed categories.

Q5: What's a healthy BMI range for older adults?
A: Some studies suggest BMI 23-27 may be optimal for older adults, as slightly higher BMI may be protective against certain conditions.