Hi Annie! The sizes are as follows:
XS: hat size up to 6-3/4 (20 to 21-3/8 inches) - petite women with short hair
One size fits most: hat size 6-7/8 to 7-3/8, (21-1/2 to -23-3/8 inches) - nearly everyone
XL: hat size 7-1/2 and up. (23-1/2 to 25 inches) - large and tall men with hair
Almost everyone fits into the one size fits most. The XS is for a small person, less than 5'3" (160cm) tall, not much hair, or an elementary/middle school age child. The XL is for big people over 6' (180cm) tall, heavy set, with a good amount of hair. The headbands do stretch, so if you are between sizes, go with the smaller size.
Nov 9, 2012