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Baby BMI Calculator

Calculate your child’s Body Mass Index (BMI) and compare it with WHO standards for children aged 0 to 5 years. Find out if their weight is appropriate for their height and age.

This tool is informational and does not replace medical advice. Always consult your baby's pediatrician.

How does this calculation work?

The baby BMI calculator is different from the adult version. In children, BMI varies significantly with age and sex, which is why it is interpreted using WHO percentile curves. The calculation divides weight (in kg) by height squared (in meters). The result is then compared to the percentile table specific to the child’s age and sex. Classifications: below p3 indicates underweight, between p3 and p85 is normal (adequate weight), between p85 and p97 suggests risk of overweight, and above p97 indicates obesity. This assessment is crucial for preventing nutritional problems and should be monitored by a pediatrician.

Frequently asked questions

Is baby BMI calculated the same way as adult BMI?▾
The formula is the same (weight ÷ height²), but the interpretation is completely different. In adults, fixed ranges are used (e.g., BMI > 25 = overweight). In children, the result is compared to percentile curves that vary by age and sex, because body composition changes during growth.
How often should I check my child’s BMI?▾
Ideally, BMI should be tracked at every routine pediatric visit, which typically occurs every 3 to 6 months during the first 2 years and annually after that. What matters most is not a single value but the trend over time. A sudden change in percentile may indicate the need for further investigation.

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