A child's shoe size can vary depending on the brand and type of shoe. It's helpful to view sizing guides when you purchase items online. Look for a link by the item information that will show international sizing as well. Trying the shoes on in the store is obviously your best bet, but if you measure your child's foot beforehand there shouldn't be a problem. Big Kids is a term used to describe a group of sizes for children.

Big Kids stands for shoe sizes for children 8 to 12 years of age. This can start from size 3 1/2 to 7, which in length is 8 5/8 to 9 3/4 inches. They are also equivalent to women's sizes from 5 to 8.5. The big kids group is also described as youth sizes.

Little Kids shoe sizing is from 4 to 8 years of age. It starts from size 10 to 3, which is 6 1/2 to 8 1/2 in inches. Toddlers tend to blend in with this group as well, with sizes 10 to 12. The little kids group is also described as youth sizes.

Toddler sizes can start at 1 1/2 and continue to size 12. This is for children from 1 to 4 years of age. These sizes measure 3 5/8 to 7 1/8 inches and are a midpoint between infant sizes and Little Kids. Due to the variation in growth in children, the toddler group has the widest range in sizing.

Infant sizes range from 1/2 to 4 and are for children up to 12 months of age. These shoes are 3 1/4 to 4 1/2 inches in length.