Clarks Youths ADVANCE Black Velcro Need help choosing your shoe size? Watch our video tutorial on how to accurately measure your feet, then use the shoe size chart below to select your size. Please note that there's no need to add sizes for growing room. One full size for growth is built into our size guide. TIP: There is no need to add sizes for growing room. One full size for growth is built into our size guide. The following table outlines the average growth rates for childrens feet, and how long you might expect a pair of shoes to fit your child correctly. Please note that this information is intended as a guide only as growth rates may vary between individuals.