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 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

Interpretation: The calculated BMI value is then categorized according to WHO standards:

• Underweight: BMI < 18.5
• Normal weight: BMI 18.5-24.9
• Overweight: BMI 25-29.9
• Obese: BMI ≥ 30

3. Importance of BMI Calculation

Details: 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. While not a direct measure of body fat, BMI correlates moderately well with more direct measures of body fat.

4. Using the Calculator

Tips: Enter weight in kilograms and height in meters. For height, you can convert from cm to m 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: Is BMI accurate for everyone?
A: BMI may not be accurate for athletes (who may have high muscle mass), pregnant women, the elderly, or those with unusual body compositions.

Q2: What are the limitations of BMI?
A: BMI doesn't distinguish between muscle and fat mass, doesn't account for fat distribution, and may not be equally applicable to all ethnic groups.

Q3: Should children use this calculator?
A: No, children and teens need age- and sex-specific BMI percentiles rather than the adult categories.

Q4: What's a healthy BMI range?
A: For most adults, 18.5 to 24.9 is considered healthy, though optimal range may vary by ethnicity.

Q5: Are there better alternatives to BMI?
A: More sophisticated measures like waist circumference, waist-to-hip ratio, or body fat percentage may provide additional information.