1. What is BMI?

Body Mass Index (BMI) is a measure of body fat based on height and weight that applies to adult men and women. It provides a simple numeric measure of a person's thickness or thinness.

2. How Does the Calculator Work?

The calculator uses the BMI formula:

Where:

• \( weight \) — Weight in pounds (converted from stones)
• \( height \) — Height in inches
• 703 — Conversion factor for imperial units

Explanation: The formula calculates body mass per unit of height squared, providing a standardized measure of body composition.

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 with more direct measures of body fat.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

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

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: Why use stones and inches?
A: This calculator uses imperial units common in the UK, where people typically measure weight in stones and pounds, and height in feet and inches.

Q4: How often should I check my BMI?
A: For most adults, checking BMI once or twice a year is sufficient unless you're actively trying to change your weight.

Q5: Should children use this calculator?
A: No, BMI interpretation for children and teens is different and considers age and sex-specific percentiles.