1. What is BMI?

Body Mass Index (BMI) is a measure that uses height and weight to work out if a person's weight is healthy. For children and teens, BMI is age- and sex-specific and is often referred to as BMI-for-age.

2. How Does the Calculator Work?

The calculator uses the standard BMI formula:

Where:

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

Explanation: The formula calculates body mass per unit of height squared to estimate body fatness.

3. Importance of BMI Calculation

Details: BMI is a simple screening tool to identify potential weight problems in adults and children. However, it doesn't directly measure body fat and should be interpreted with caution in muscular individuals.

4. Using the Calculator

Tips: Enter weight in pounds and height in inches. For children, BMI should be plotted on a growth chart to determine the percentile for age and sex.

5. Frequently Asked Questions (FAQ)

Q1: Is BMI different for children?
A: Yes, children's BMI is interpreted relative to other children of the same age and sex using percentile charts.

Q2: What are the BMI categories for adults?
A: Underweight (<18.5), Normal weight (18.5-24.9), Overweight (25-29.9), Obese (≥30).

Q3: When should BMI be measured in children?
A: The NHS recommends measuring BMI annually as part of routine child health assessments.

Q4: Are there limitations to BMI?
A: BMI doesn't distinguish between muscle and fat, so athletes may have high BMI without excess fat.

Q5: What should I do if my child's BMI is high?
A: Consult your GP or health visitor who can assess growth patterns and provide appropriate advice.