We created our hats as a one size fits most. As you can see in our photos, the hats will fit both younger children and youth due to the snapback detail. If you're considering twinning with your kiddo, it also fits most adult heads. We chose a snapback style so that you can continue to adjust it as your child grows. Head sizes vary considerably, so it’s best to measure the intended user’s head by measuring around the head above the ears. If you land between 21 1/8" to 23 1/3" inches in circumference, your hat will fit. Our hat size range is 6 3/4 to 7 1/2.