1. What is Body Mass Index (BMI)?

Body Mass Index (BMI) is a simple index of weight-for-height that is commonly used to classify underweight, 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)

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. It is strongly correlated with various metabolic and disease outcomes.

4. Using the Calculator

Tips: Enter weight in kilograms, height in meters, and age in years. All values must be valid (weight > 0, height > 0, age between 1-120).

5. Frequently Asked Questions (FAQ)

Q1: What are the BMI categories for adults?
A: Underweight: <18.5, Normal weight: 18.5–24.9, Overweight: 25–29.9, Obesity: ≥30.

Q2: Does BMI interpretation change with age?
A: Yes, for older adults, a slightly higher BMI (24-29) may be healthier than a lower BMI.

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

Q4: Is BMI accurate for athletes?
A: BMI may overestimate body fat in athletes and others who have a muscular build.

Q5: Should children use the same BMI categories?
A: No, BMI for children and teens is interpreted differently using age and sex-specific percentiles.