My son measured a size 7, so that is what I ordered. They were pretty big on him. Not so big that he cannot wear them, but he could have used a half size smaller, at least. On the plus side, they will definitely last all summer this way. He also has pretty fat little feet and these fit really well. They are adjustable in the toe width and ankle width, so they fit really well. He loves them. They have support, which is great for a toddler. (They have enough trouble staying vertical without the added difficulty of bad shoes.) They are very durable. He'll have to try very, very hard to destroy these. Well worth the money.