1. What is BMI?

Body Mass Index (BMI) is a measure of body fat based on height and weight that applies to children and adults. For children, 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 kilograms (kg)
• \( height \) — Height in meters (m)

Explanation: The result is then plotted on UK growth charts to determine the percentile for the child's age and gender.

3. Importance of BMI Calculation

Details: BMI-for-age is the recommended measure for screening overweight and obesity in children aged 2-18 years. It helps identify potential weight problems that may lead to health issues.

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 taken with minimal clothing and no shoes.

5. Frequently Asked Questions (FAQ)

Q1: What do BMI percentiles mean?
A: Below 2nd percentile: underweight; 2nd to 91st: healthy weight; 91st to 98th: overweight; Above 98th: obese (UK90 charts).

Q2: How often should children's BMI be checked?
A: NHS recommends annual checks as part of the National Child Measurement Programme for children aged 4-5 and 10-11.

Q3: Are there limitations to BMI?
A: BMI doesn't distinguish between muscle and fat, so very muscular children may have high BMI without excess fat.

Q4: What growth charts are used in the UK?
A: The UK-WHO growth charts combine UK90 data with WHO standards for optimal growth.

Q5: Where can I plot my child's BMI?
A: The Royal College of Paediatrics and Child Health provides printable growth charts for healthcare professionals and parents.