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 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: The 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 noninvasive surrogate measure of body fat. While it doesn't measure body fat directly, research has shown that BMI correlates to direct measures of body fat such as underwater weighing and dual-energy x-ray absorptiometry (DXA).

4. Using the Calculator

Tips: Enter weight in kilograms and height in meters. For height, you can convert from centimeters by dividing by 100 (e.g., 175 cm = 1.75 m). 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, or racial and sex differences.

Q4: Should children use this calculator?
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, but individual circumstances may vary.