All hats are custom crocheted to order. Sizing information (measure from center of forehead all the way around the head):
 
SMALL = head circumference 16"- 18" (3 months to 11 month old child)
MEDIUM = head circumference 19"- 20" (1 year to 3 year old child)
LARGE = head circumference 21" - 22" (4 year old child through adult)