1. What is 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 the weight in kilograms divided by the square of the 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 a simple, inexpensive screening method for weight category—underweight, healthy weight, overweight, and obesity. BMI does not measure body fat directly, but research has shown that BMI is moderately correlated with more direct measures of body fat.

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 ≥ 18).

5. Frequently Asked Questions (FAQ)

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

Q2: Is BMI different for children and teens?
A: Yes, BMI for children and teens is age- and sex-specific and is often referred to as BMI-for-age.

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

Q4: Should athletes use BMI?
A: BMI may overestimate body fat in athletes and others who have a muscular build.

Q5: What's a healthy BMI for older adults?
A: Some research suggests that a BMI between 23-27 may be optimal for older adults (65+ years).