Patagonia Hats Size chart

 Size
Adult Head Circumference
Women's
One Size
21¾"-24" (55-61cm)
21¼"-23¼" (54-59cm)
Small/Medium
21¾"-22¾" (55-58cm)
21¼"-22" (54-56cm)
Large/Extra Large
22¾"-24" (58-61cm)
22"-23¼" (54-59cm)

Measurements refer to body size, not garment dimensions, unless otherwise noted.