1. What is BMI?

Body Mass Index (BMI) is a value derived from the mass and height of a person. It provides a simple numeric measure of a person's thickness or thinness, allowing health professionals to discuss weight problems more objectively with their patients.

2. How Does the Calculator Work?

The calculator uses the BMI formula for stone weight:

Where:

• \( weight \) — Weight in stones (1 stone = 14 pounds)
• \( height \) — Height in inches
• 703 — Conversion factor (kg/m² to lb/in²)

Explanation: The formula converts stone weight to pounds, then calculates the ratio of weight to height squared with appropriate unit conversion.

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 stones (e.g., 10.5 for 10 stone 7 pounds) and height in inches (e.g., 68 for 5 feet 8 inches). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Why use stone weight measurement?
A: This calculator is designed for regions where stone weight is commonly used (primarily UK and Ireland). 1 stone equals 14 pounds or approximately 6.35 kg.

Q2: How accurate is BMI?
A: BMI is a useful screening tool but doesn't account for muscle mass, bone density, or fat distribution. Athletes may have high BMI without excess fat.

Q3: What are the limitations of BMI?
A: BMI doesn't distinguish between muscle and fat, and may not be accurate for children, pregnant women, the elderly, or certain ethnic groups.

Q4: Should BMI be used alone for health assessment?
A: No, BMI should be used alongside other measurements like waist circumference and body composition analysis for a complete health assessment.

Q5: How often should I check my BMI?
A: For most adults, checking BMI every few months is sufficient unless you're actively trying to change your weight.