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 BMI is Calculated

The calculator uses the standard BMI formula:

Where:

• \( weight \) — Body weight in kilograms
• \( height \) — Height in meters

3. BMI Categories

For adults 20 years old and older:

• Underweight: BMI less than 18.5
• Normal weight: BMI 18.5 to 24.9
• Overweight: BMI 25 to 29.9
• Obese: BMI 30 or greater

4. Using the Calculator

Tips: Enter weight in kilograms, height in meters, and age in years. For adults only (age 18+). All values must be valid (weight > 0, height > 0, age ≥18).

5. Frequently Asked Questions (FAQ)

Q1: Is BMI accurate for everyone?
A: BMI may not accurately reflect body fat in athletes (who have more muscle) or older people (who may have lost muscle).

Q2: What's a healthy BMI for my age?
A: For adults, the healthy range (18.5-24.9) is the same for all ages, though older adults may be healthier at slightly higher BMIs.

Q3: Should I use different calculations for children?
A: Yes, children and teens need BMI-for-age percentiles that account for growth patterns and sex differences.

Q4: What are the limitations of BMI?
A: BMI doesn't distinguish between muscle and fat, and doesn't account for fat distribution (e.g., abdominal fat).

Q5: What should I do if my BMI is high?
A: Consult a healthcare provider for a full assessment. They may recommend body composition analysis and lifestyle changes.