How many strips a roll width creates
Ceil of wall width divided by roll width, with a short last strip.
Strips = ceiling of wall width ÷ roll width. A 400 cm wall and a 53 cm roll need 8 strips, and the last one is 29 cm wide. A wider 70 cm roll needs 6 strips (5 × 70 = 350, last strip 50 cm). Buying the wider roll can mean fewer drops and less matching, which matters more on a half drop than on a plain paper.
If one strip is longer than the roll, the tool stops and says so. It will not silently split a drop into two pieces. Shorten the allowance or pick a longer roll.
Build the cut list on export and print it. Ads and the site header are hidden in the print stylesheet so the list can go to the workshop.