Considering this is for an adult, I would say it runs on the small side.  My daughter does not have what would be considered a big head (or big hair), and yet this barely fit.  She does have thick hair, but wears it flat and straight.  But we made it work, and the tassel is the main thing she wants to hold on to for a keepsake.  It is good quality (other than running small). We used this in our homeschool graduation and it really added to make it a special moment.