Question 1

What growth chart standard does this calculator use?

Accepted Answer

This calculator uses the CDC-published, WHO-based LMS reference data for children 0–36 months old, the same standard the CDC recommends U.S. pediatricians use for children under 2 years of age. It covers weight-for-age, length-for-age, and head-circumference-for-age.

Question 2

What does "percentile" mean for my baby's growth?

Accepted Answer

A percentile shows how your baby compares to other babies of the same age and sex. For example, a weight in the 60th percentile means your baby weighs more than about 60% of babies the same age and sex, and less than about 40%. A single percentile is not "good" or "bad" on its own — consistent tracking over time matters more than any one number.

Question 3

Is my baby's percentile a diagnosis?

Accepted Answer

No. This tool is for general informational and tracking purposes only and is not a substitute for professional medical advice. Percentiles below the 3rd or above the 97th are worth discussing with your pediatrician, but only a doctor examining your baby's full growth history and health can assess whether there is cause for concern.

Question 4

Why does the same weight give a different percentile for boys and girls?

Accepted Answer

Boys and girls grow at different average rates and have separate reference tables (separate L, M, S values at every age). The calculator automatically applies the correct table based on the sex you select.

Question 5

What if my baby's age isn't a whole number of months?

Accepted Answer

Enter a decimal value — for example, 7.5 for seven-and-a-half months. The calculator linearly interpolates between the nearest reference ages for an accurate result at any age from 0 to 36 months.

Percentile Range	What it Means
< 3rd	Below the typical range — worth discussing at your next pediatric visit
3rd – 10th	Lower end of the typical range
10th – 90th	Typical range for age and sex
90th – 97th	Higher end of the typical range
> 97th	Above the typical range — worth discussing at your next pediatric visit

Baby Growth Percentile Calculator

Baby's Details

Results

Understanding Growth Percentile Ranges

Frequently Asked Questions

What growth chart standard does this calculator use?

What does "percentile" mean for my baby's growth?

Is my baby's percentile a diagnosis?

Why does the same weight give a different percentile for boys and girls?

What if my baby's age isn't a whole number of months?

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