def calculate_bmi(weight_kg, height_m):
    """
    Calculate Body Mass Index (BMI)
    
    Parameters:
    weight_kg (float): Weight in kilograms
    height_m (float): Height in meters
    
    Returns:
    float: BMI value in kg/m²
    """
    if height_m <= 0:
        raise ValueError("Height must be greater than zero")
    return weight_kg / (height_m ** 2)

# Example usage:
weight = 70.5  # kg
height = 1.75  # meters
bmi = calculate_bmi(weight, height)
print(f"BMI: {bmi:.1f} kg/m²")
                        

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 BMI is Calculated

The BMI calculation formula is:

Where:

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

Explanation: The calculation divides a person's weight in kilograms by the square of their height in meters.

3. BMI Categories

Standard BMI Categories:

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

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).

5. Frequently Asked Questions (FAQ)

Q1: Is BMI accurate for everyone?
A: BMI may not be accurate for athletes (high muscle mass), pregnant women, or the elderly (muscle loss).

Q2: What's a healthy BMI range?
A: For most adults, 18.5 to 24.9 is considered healthy.

Q3: How often should I check my BMI?
A: Periodic checks (every few months) are sufficient unless undergoing significant weight changes.

Q4: Can children use this calculator?
A: Children need age- and sex-specific BMI percentiles rather than adult categories.

Q5: What are alternatives to BMI?
A: Waist-to-hip ratio, body fat percentage, or DEXA scans provide more detailed body composition analysis.