This is a kuffie( Islamic hat), sewn for babies 0-to 18 month. Since picking a size might be a little hard on this sight I am going to make it a little easier by saying x-small is size 14 1/2 to 15''. Small is size 16and 17''. Medium is size 18 1/2 -19''. large is size 20''. To make it easier for me I will match the kuffie to the size shirt you order. So if you order size small I will sew a size small kuffie.