Standard Sizing (CM)
JR XS	49-53
JR S	53-56
JR M	56-59
XS	49-53
S	53-56
M	56-59
L	59-62
XL	62-64

 
Helmet sizing is determined by the distance around your head in centimeters.  Measure the circumference of your head just above your eyebrows to determine your correct helmet size.