Havplenty,
Thank you for this site. It has a lot of helpful information.
"a turnover is a 6" triangle so cutting your fabric into 6" squares and cutting these in half diagonally should create the turnovers you are looking for.
info contained on this website.
"...Turnovers - Hot out of the oven, Turnovers are 40, 6-inch squares cut in half diagonally to yield 80 half square triangles."
here is a really tip helpful site and they have a precut guide downloaded chart at 9.201"