Infant: 0-3 Toddler
Extra Small: 4-6 Toddler
Small: 7-10 Toddler
Medium: 10-13 Toddler/Kids
Large: 1-7 Big Kids/Womens 4-10/Mens 4-8
Sizes Infant/XXS, Extra Small, Small + Medium have "BOO" grips on the bottom of the feet and size large have a stitched "BOO" on the bottom of the feet.