To achieve the best fit for your little one's new Cabooties, we recommend carefully measuring your baby's foot. For the best results, stand your baby or toddler on a piece of white paper and carefully mark the end of their toe and back of their heel. Measure the distance between these marks and add a half inch. Use this length to select your babe's size from the size chart below. If your child is in between sizes, we recommend choosing the larger size.