For my roll, which is 6 inches in diameter, I went up 3.5 inches from the bottom, then 3.5 inches in from the front edge to keep it entirely within the frame of the holder.

Wavy edges, Weaver said, are designed to solve the No. 1 problem consumers have with toilet paper: the incomplete tear. The dreaded incomplete tear. Photo illustration by Slate. Photo by Dan Kois.

Cut the leading edge of the new roll of paper to give it a straight edge. Do not feed the paper roll into the Sharp El-1801-P calculator with a torn edge.