1. What is BMI?

Body Mass Index (BMI) is a measure that uses height and weight to estimate body fat. For children, BMI is age and sex-specific and is often referred to as BMI-for-age.

2. How BMI is Calculated for Children

The calculator uses the standard BMI formula:

Where:

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

Note: For children, the raw BMI value is then plotted on gender-specific growth charts to determine the percentile.

3. Importance of BMI for UK Kids

Details: BMI screening helps identify children who are underweight, overweight, or obese. In the UK, BMI percentiles are used to assess healthy growth patterns.

4. Using the Calculator

Tips: Enter weight in kilograms and height in meters. For accurate results, measurements should be taken with minimal clothing and no shoes.

5. Frequently Asked Questions (FAQ)

Q1: How does BMI differ for children vs adults?
A: Children's BMI is interpreted relative to other children of the same age and sex using percentile charts rather than fixed categories.

Q2: What are the UK BMI percentile categories?
A: Generally: <2nd (underweight), 2nd-91st (healthy), 91st-98th (overweight), >98th (obese).

Q3: Why is clothing irrelevant for BMI calculation?
A: BMI is based on body measurements, not clothing size. Children's clothing sizes vary widely between brands and don't correlate precisely with body composition.

Q4: How often should children's BMI be checked?
A: The UK National Child Measurement Programme measures children in Reception (age 4-5) and Year 6 (age 10-11).

Q5: Are there limitations to BMI for children?
A: BMI doesn't distinguish between fat and muscle mass. Athletic children may have higher BMI without excess fat.