1. What is BMI?

Body Mass Index (BMI) is a simple calculation using a person's height and weight. The formula is BMI = kg/m² where kg is a person's weight in kilograms and m² is their height in meters squared. BMI provides a reliable indicator of body fatness for most people.

2. How Does the Calculator Work?

The calculator uses the standard BMI formula:

Where:

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

Python Implementation:

def calculate_bmi(weight_kg, height_m):
    return weight_kg / (height_m ** 2)

# Example usage:
weight = 70  # kg
height = 1.75  # meters
bmi = calculate_bmi(weight, height)
print(f"BMI: {bmi:.1f} kg/m²")
                    

3. Importance of BMI Calculation

Details: BMI is a simple, inexpensive screening method for weight category—underweight, healthy weight, overweight, and obesity. It correlates with direct measures of body fat and is strongly associated with various metabolic and disease outcomes.

4. Using the Calculator

Tips: Enter weight in kilograms and height in meters. For height in centimeters, divide 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 standard BMI categories?
A: Underweight (<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 underestimate it in older persons who have lost muscle mass.

Q3: What are the limitations of BMI?
A: Doesn't distinguish between muscle and fat, doesn't account for fat distribution, and may not be accurate for certain ethnic groups.

Q4: Should children use the same BMI categories?
A: No, children and teens need age- and sex-specific percentiles rather than the adult categories.

Q5: What's a healthy BMI range?
A: For most adults, 18.5 to 24.9 is considered healthy, but individual circumstances may vary.