How to Use the Baby Growth Percentile Calculator
A growth percentile shows where your baby ranks compared to 100 babies of the same age and sex. Enter your baby's age, sex, height, and weight, and this calculator estimates height and weight percentiles using a statistical curve approximating the CDC growth charts (with WHO standards commonly used for the 0-2 year range, which is standard U.S. pediatric practice).
For example, a weight percentile of 25 means your baby weighs more than roughly 25 out of 100 same-age peers, while 75 means they weigh more than most. Generally, the 3rd to 97th percentile range is considered typical, and even values outside that range can be perfectly normal depending on parental build and individual growth patterns. What matters most clinically is the trend over time, not a single measurement.
This tool uses an approximated statistical model of standard growth charts for reference only — it does not replace the precise growth charts and clinical judgment used in a pediatrician's office. Premature babies should be evaluated using corrected age, and any baby whose percentile shifts sharply over a short period, or stays consistently below the 3rd or above the 97th percentile, should be seen by a pediatrician for a proper evaluation.
Frequently Asked Questions
Not necessarily. A percentile just shows where your baby ranks compared to peers, and anywhere from the 3rd to 97th percentile is generally considered a normal range. What matters more than a single number is a sudden jump or drop across percentile lines, or values that stay below the 3rd or above the 97th percentile — see a pediatrician if you notice that.
Premature babies should be measured using corrected age (based on the due date, not the birth date) for an accurate comparison. This calculator assumes a full-term baby, so premature infants should be evaluated separately by a pediatrician.