1. What is BMI for Children?

BMI (Body Mass Index) for children and young people is calculated the same way as for adults, but the results are interpreted differently. For children, BMI is compared against growth charts that take into account age and sex.

2. How the Calculator Works

The calculator uses the standard BMI formula:

Where:

• \( weight \) — Body weight in kilograms
• \( height \) — Height in meters

Note: For children, the BMI number is plotted on NHS growth charts to determine the percentile for their age and sex.

3. Understanding BMI Percentiles

Details: Percentiles show how a child's BMI compares to others of the same age and sex:

• Below 2nd percentile: Underweight
• 2nd to 90th percentile: Healthy weight
• 91st to 97th percentile: Overweight
• Above 98th percentile: Very overweight (obese)

4. Using the Calculator

Tips: Enter weight in kg, height in meters, age in years (2-18), and select gender. For accurate results, measurements should be recent.

5. Frequently Asked Questions (FAQ)

Q1: Why is BMI different for children than adults?
A: Children's body composition changes as they grow, so BMI must be interpreted relative to other children of the same age and sex.

Q2: How often should my child's BMI be checked?
A: The NHS recommends measuring BMI annually as part of routine health checks.

Q3: What if my child is very muscular?
A: BMI may overestimate body fat in muscular children. Additional assessments may be needed.

Q4: Where can I find official NHS growth charts?
A: NHS growth charts are available through your GP or at rcpch.ac.uk

Q5: What should I do if concerned about my child's BMI?
A: Consult your GP or school nurse for personalized advice and monitoring.