Motorcycle Helmet Sizing Chart
Helmet Size	Head Cir. (IN)	Head Cir. (CM)	Hat Size
2X-Small	20-1/2	52	6-1/2
X-Small	20-7/8 - 21-1/4	53 - 54	6-5/8 - 6-3/4
Small	21-5/8 - 22	55 - 56	6-7/8 - 7
Medium	22-7/16 - 22-13/16	57 - 58	7-1/8 - 7-1/4
Large	23-1/4 - 23-5/8	59 - 60	7-3/8 - 7-1/2
X-Large	24 - 24-3/8	61 - 62	7-5/8 - 7-3/4
2X-Large	24-13/16 - 25-3/16	63 - 64	7-7/8 - 8
3X-Large	25-9/16 - 26	65 - 66	8-1/8 - 8-1/4