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
• \( height \) — Height in meters

For weight loss percentage: \[ \text{Weight Loss %} = \frac{\text{Initial Weight} - \text{Current Weight}}{\text{Initial Weight}} \times 100 \]

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.

4. Using the Calculator

Tips: Enter weight in kilograms, height in meters. For weight loss percentage, include your initial weight. All values must be valid (weight > 0, height > 0).

5. Frequently Asked Questions (FAQ)

Q1: What are the BMI categories?
A: Underweight (<18.5), Normal weight (18.5-24.9), Overweight (25-29.9), Obesity (≥30).

Q2: Is BMI accurate for everyone?
A: BMI may not be accurate for athletes (high muscle mass), pregnant women, or the elderly.

Q3: What is a healthy weight loss percentage?
A: A 5-10% weight loss can significantly improve health markers for overweight individuals.

Q4: How often should I check my BMI?
A: For most adults, checking every few months is sufficient unless under medical supervision.

Q5: Should children use this calculator?
A: No, children and teens need age- and sex-specific BMI percentile calculations.