BMI Formula:
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BMI (Body Mass Index) for children and teens is calculated the same way as for adults, but the interpretation is different. For children, BMI is age- and sex-specific and is often referred to as BMI-for-age.
The calculator uses the standard BMI formula:
Where:
Note: For children, the BMI number is plotted on the CDC BMI-for-age growth charts to determine the corresponding percentile.
Details: BMI-for-age is the recommended measure for screening overweight and obesity in children and teens. It's a reliable indicator of body fatness for most children.
Tips: Enter weight in kilograms, height in meters, age in years (2-20), and select gender. For accurate results, measurements should be taken with proper technique.
Q1: Why is BMI interpreted differently for children?
A: Children's body composition varies as they grow, and between boys and girls. BMI-for-age accounts for these differences.
Q2: What are the BMI categories for children?
A: Underweight (<5th percentile), Healthy weight (5th-85th), Overweight (85th-95th), Obese (≥95th percentile).
Q3: How often should children's BMI be checked?
A: The AAP recommends BMI screening annually starting at age 2.
Q4: Are there limitations to BMI for children?
A: BMI doesn't distinguish between fat and muscle mass. Athletic children may have high BMI without excess fat.
Q5: Where can I find CDC growth charts?
A: CDC growth charts are available on the CDC website for clinical use in interpreting BMI-for-age.