Measure your head to determine your cap size

Cap Size	Front to back	Ear to ear	Circumfence
Petite (4)	~14" (~35.5 cm)	~13.2" (~33.5 cm)	~21.3" (~54 cm)
Standard (5)	~14.2" (~36 cm)	~13.4" (~34 cm)	~21.7" (~55 cm)
Large (6)	~14.4" (~36.5 cm)	~13.6" (~34.5 cm)	~22" (~56 cm)