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
• \( height \) — Height in meters

Explanation: The calculator also converts the weight from kilograms to stone (1 stone = 6.35029 kg).

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, you can convert from cm to m by dividing by 100 (e.g., 175 cm = 1.75 m). The calculator defaults to 80 kg (12.6 stone).

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, or the elderly who may have lost muscle mass.

Q2: How do I convert stone to kilograms?
A: Multiply stone by 6.35029 to get kilograms (1 stone = 6.35029 kg).

Q3: What's a healthy BMI range?
A: For most adults, a healthy BMI is between 18.5 and 24.9.

Q4: Why is 80 kg used as default?
A: 80 kg (12.6 stone) is a common weight reference point for BMI calculations.

Q5: Should children use this calculator?
A: No, children and teens need age- and sex-specific BMI percentiles rather than the adult categories.