AFX Adult Helmet Sizing

Manufacturer's Suggested Size Chart (Not a guarantee of fit) 
Size Inches Centimeters  Hat Size
XS 21(1/4) - 21(5/8) 54 - 55 6(3/4) - 6(7/8)
SM 22 - 22(7/16) 56 - 57 7 - 7(1/8)
MD 22(13/16) - 23(1/4) 58 - 59 7(1/4) - 7(3/8)
LG 23(5/8) - 24 60 - 61 7(1/2) - 7(5/8)
XL 24(3/8) - 24(13/16) 62 - 63 7(3/4) - 7(7/8)
2XL 25(3/16) - 25(5/8) 64 - 65 8 - 8(1/8)
3XL 26 - 26(3/8) 66 - 67 8(1/4) - 8(3/8)
4XL 26(3/4) - 27(1/8) 68 - 69 8(1/2) - 8(5/8)