All of our Grow with me Pants have a generous fit . We do not recommend sizing up . 12-3y on average fits up to size 4T , 3y-6y up to size 7 , 6y-9y up to size 10 ! Our grow with me pants have a unique fit that we have worked onadjusting for a few year . We think this is our best fit to date ! Our leggings feature a slimmer fit that gets tighter with growth and our harems have a drop crotch fit that gets slender in the legs !