Non CPSC	Helmet Sizing
	Head Circumference	Hat Size
S	20 1/4" 52 cm	6 1/2
M	21 1/4" 54 cm	6 3/4
L	22 3/4" 54 cm	7 1/4

CPSC  CE Certified	Helmet Sizing
	Head  Circumference	Hat Size
S/M	20" / 51 cm 20 7/8" / 53 cm	6 3/8 6 3/8
L/XL	21 5/8" / 55 cm 22 3/8" / 57 cm 23 5/8" / 60 cm	6 7/8 7 1/8 7 1/2

Please note that CPSC helmets are adjustable because they come with extra padding pieces to customize fit.