Finished size (unfolded brim, laid flat. Please note that these hats stretch a lot wider when worn due to ribbing. These measurements are meant as a guide while creating):

Small (toddler): 16 cm wide by 26 cm long
Medium (child to small adult): 17 cm wide by 26 cm long
Large (ladies): 18 cm wide by 29 cm long
Extra Large (mens): 19 cm wide by 32 cm long