Sizing:
Infant: 0-3 Toddler 
Extra Small: 4-6 Toddler
Small: 7-10 Toddler
Medium: 10-13 Toddler/Kids
Large 1-7 Kids Shoe Size/Womens 4-8/Mens 4-6 Shoe Size

Sizes Infant/XXS, Extra Small, Small + Medium have "To Infinity and Beyond" on the bottom of the feet and size large have a stitched "To Infinity and Beyond" on the bottom of the feet.