Our helmets come in one size at the moment: female M (typically 52~58cm).  To measure your head circumference, place a cloth tape measure in the center of your forehead, measure all the around your head as per diagram below. 

how to measure head for helmet size

Sawako helmet has a dial-to-fit size adjuster at the back which should make the helmet fit you snugly (here is how to use it). 

If you feel you need extra padding, please contact order@sawako.com