Baby Growth Percentile Calculator
Estimate where your baby’s weight falls compared to typical growth standards for their age, using an approximate z-score method.
What growth percentiles mean
Growth percentiles show how a baby’s measurement, such as weight, compares to a reference population of babies the same age and sex. A 50th percentile means the baby’s weight is right at the typical average; higher or lower percentiles show how far above or below average they fall.
How this calculator works
This calculator approximates an expected average weight for the entered age and sex, then calculates a z-score (how many standard deviations the entered weight is from that average) and converts it to an approximate percentile using the standard normal distribution.
This is a simplified educational approximation, not the official WHO or CDC growth chart calculation, and individual growth patterns vary widely and normally. Always use official growth charts and a pediatrician for actual clinical growth assessment.