1. What is BMI?

BMI (Body Mass Index) 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: 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 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 and height in meters. All values must be valid (weight > 0, height > 0). For most accurate results, measure height without shoes and weight in light clothing.

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 others with muscular builds and underestimate it in older persons who have lost muscle mass.

Q3: Should children use this calculator?
A: No, children and teens need age- and sex-specific percentiles because their body composition varies as they grow.

Q4: What are limitations of BMI?
A: BMI doesn't distinguish between muscle and fat, doesn't account for fat distribution, and may not be accurate for certain ethnic groups.

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