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Child BMI Calculator

Calculate BMI for children and teens (ages 2-20) and interpret the result based on age and sex percentiles.

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Result

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Formula

Weight (kg) / [Height (m)]^2

Calculates the raw Body Mass Index. For children, the raw number is then compared to a growth chart of other children of the same age and sex.

Worked Example

8 year old boy, 25kg, 125cm -> BMI 16.0.

Frequently Asked Questions

Why use percentiles?

Children's body fat levels change as they grow, and differ between boys and girls. Raw BMI numbers are less meaningful than where they fall relative to peers.

What are the categories?

Healthy weight: 5th to <85th percentile; Overweight: 85th to <95th percentile; Obesity: 95th percentile or greater.

Is BMI always accurate?

It is a screening tool, not a diagnosis. A child with high muscle mass may have a high BMI without having high body fat.

Medical Disclaimer

This calculator is provided for informational and educational purposes only. It is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making any decisions based on these results. Do not disregard or delay seeking medical advice because of information obtained from this tool.

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