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)

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, and non-invasive surrogate measure of body fat. While it doesn't directly measure body fat, it correlates moderately well with more direct measures of body fat. It's used to screen for weight categories that may lead to health problems.

4. Using the Calculator

Tips: Enter weight in kilograms and height in meters. For pounds and inches, convert first (1 kg = 2.2 lbs, 1 m = 39.37 inches). All values must be valid (weight > 0, height > 0).

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), Obese (≥30).

Q2: Is BMI accurate for everyone?
A: BMI may overestimate body fat in athletes and those with muscular builds, and underestimate it in older persons who have lost muscle mass.

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: Should children use the same BMI categories?
A: No, children and teens need age- and sex-specific percentiles because their body composition varies as they grow.

Q5: What's a healthy BMI range?
A: For most adults, 18.5 to 24.9 is considered healthy, though optimal may vary by individual factors.