1. What is BMI for Children?

BMI (Body Mass Index) for children and teens is age- and sex-specific and is often referred to as BMI-for-age. Unlike adults, children's body composition varies as they age and differs between boys and girls, so their BMI needs to be compared against growth charts specific to their age and gender.

2. How Does the Calculator Work?

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 growth charts to determine a percentile ranking compared to children of the same age and gender.

3. Importance of BMI Calculation

Details: BMI-for-age is the recommended indicator for screening overweight and obesity in children and teens. It's a reliable indicator of body fatness for most children, though it doesn't measure body fat directly.

4. Using the Calculator

Tips:

• Measure weight accurately with minimal clothing
• Measure height without shoes
• Use the child's exact age
• For children under 2 years, use weight-for-length charts instead

5. Frequently Asked Questions (FAQ)

Q1: What BMI percentile indicates overweight in children?
A: For children 2-18 years: 85th to 94th percentile = overweight; 95th percentile or higher = obesity.

Q2: How often should children's BMI be checked?
A: The NHS recommends annual BMI checks for children aged 2-18 as part of routine health assessments.

Q3: Are there limitations to BMI for children?
A: BMI may overestimate body fat in muscular children and underestimate it in children who have lost muscle mass.

Q4: Where can I find NHS growth charts?
A: NHS growth charts are available at RCPCH website.

Q5: What should I do if my child's BMI is high?
A: Consult your GP or health visitor for assessment. They may consider other factors like growth pattern, diet, and activity levels.