All shoe sizes will be sized by number any shoes infant thru kids will be size 0-13 any shoes sized for big kids will be sized with a Y for youth. Big Kid Sizes 1Y and up. We generally take shoes up to a Womens or Mens size 7 these would be sized (Size 7Y). We hope this will help with sizing up shoes for your order, feel free to message us with any questions. Happy Shopping!!