HJC Helmet Sizing

Manufacturer's Suggested Size Chart (Not a guarantee of fit) 
SizeCentimeterHat SizeInches
2XS 51 - 52 6(3/8) - 6(1/2) 20 - 20(1/2)
XS 53 - 54 6(5/8) - 6(3/4) 20(7/8) - 21(1/4)
SM 55 - 56 6(7/8) - 7 21(5/8) - 22
MD 57 - 58 7(1/8) - 7(1/4) 22(1/2) - 22(7/8)
LG 59 - 60 7(3/8) - 7(1/2) 23(1/4) - 23(5/8)
XL 61 - 62 7(5/8) - 7(3/4) 24 - 24(3/8)
2XL 63 - 64 7(7/8) - 8 24(3/4) - 25(1/4)
3XL 65 - 66 8(1/8) - 8(1/4) 25(5/8) - 26
4XL 67 - 68 8(3/8) - 8(1/2) 26(3/8) - 26(3/4)
5XL 69 - 70 8(3/4) - 8(3/4) 27(1/4) - 27(5/8)