This tip makes it easy.
After all that folding, youll be left with a piece of parchment that sort of resembles a necktie.
Put the tip of it in the center of the cake pan, and trim along the very edge.
Unfold the whole thing and voila: You have a parchment circle thatll fit every time.
Video: The Easiest Way to Line a Round Cake Pan with Parchment Paper| Food & Wine