1. What is BMI?

BMI (Body Mass Index) is a measure of body fat based on height and weight that applies to adult men and women. It's a simple screening tool to identify possible weight problems.

2. How Does the Calculator Work?

The calculator uses the UK stone formula:

Where:

• \( weight \) — Weight in stones (UK measurement)
• \( height \) — Height in inches
• 14 — Conversion factor from stone to pounds
• 703 — Conversion factor from (lbs/in²) to kg/m²

3. BMI Categories

Standard BMI Categories:

• Underweight: BMI less than 18.5
• Normal weight: BMI 18.5 to 24.9
• Overweight: BMI 25 to 29.9
• Obese: BMI 30 or greater

4. Using the Calculator

Tips: Enter weight in stones (UK measurement) and height in inches. All values must be valid (weight > 0, height > 0).

5. Frequently Asked Questions (FAQ)

Q1: Why use stone and inches measurements?
A: This calculator is specifically designed for the UK where stone is commonly used for body weight and feet/inches for height.

Q2: Is BMI accurate for everyone?
A: BMI may overestimate body fat in athletes and underestimate it in older people who have lost muscle mass.

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

Q4: Should children use this calculator?
A: No, children and teens need BMI-for-age percentiles that account for growth patterns.

Q5: What are the limitations of BMI?
A: BMI doesn't distinguish between muscle and fat, and doesn't account for fat distribution.