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:

Where:

• \( weight \) — Weight in pounds (converted from stone)
• \( height \) — Height in inches
• 703 — Conversion factor (kg/m² to lb/in²)

Explanation: The equation calculates body mass relative to height squared, providing a standardized measure of body weight.

3. Importance of BMI Calculation

Details: BMI is widely used as a screening tool to identify possible weight problems in adults. While it doesn't measure body fat directly, research has shown that BMI correlates to direct measures of body fat.

4. Using the Calculator

Tips: Enter weight in stone and height in inches. All values must be valid (weight > 0, height > 0). The calculator automatically converts stone to pounds for the calculation.

5. Frequently Asked Questions (FAQ)

Q1: What are the BMI categories?
A: Underweight (<18.5), Normal weight (18.5-24.9), Overweight (25-29.9), Obesity (≥30).

Q2: Are there limitations to BMI?
A: BMI doesn't account for muscle mass, bone density, overall body composition, or racial and sex differences.

Q3: Why use stone and inches?
A: This calculator is designed for the UK where stone is commonly used for body weight measurement.

Q4: How accurate is BMI for athletes?
A: BMI may overestimate body fat in athletes with high muscle mass and underestimate it in older people with lost muscle mass.

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