A percentile tells you how your baby's measurement compares to other babies of the same age and sex. For example, if your baby is at the 50th percentile for weight, it means about half of babies weigh more and half weigh less.

A high or low percentile does not mean something is wrong. Babies come in all sizes. What matters most is that your baby is growing consistently along their own curve over time. A baby at the 15th percentile who stays near the 15th percentile is typically growing well.

Talk to your pediatrician if your baby's percentile changes significantly between visits (for example, dropping from the 50th to the 10th percentile), or if measurements fall below the 3rd or above the 97th percentile.

This calculator uses WHO Child Growth Standards, the international reference recommended by the CDC for children under 2 years old.