**Weight Percentile Chart**. Percentiles divide up the range of typical growth on growth charts. Body mass index ( bmi) is a value derived from the mass (weight) and height of a person.

In order to obtain local percentiles, enter in the yellow field below the mean birthweight at 40 weeks. A child that falls on the 75th percentile is bigger than 75% of children of the same age while 25% of children are larger. The thick red line in the middle is the 50 th percentile, which indicates that 50% of the women population have a weight that is heavier than the line and 50% are lighter.