Rolls of wallpaper needed for a room.
Free to use, no sign-up required. Wallpaper Estimator is one of 198 tools built into Xenition, alongside a chat that can use them for you.
Works out how many rolls of wallpaper a room needs by counting the vertical strips around the walls and how many fit on each roll.
Strips = perimeter ÷ roll width, rounded up. Strips per roll = roll length ÷ wall height, rounded down, since a short offcut cannot be a drop. Rolls = strips ÷ strips per roll, rounded up, plus one if the spare is ticked.
An 18 m perimeter, 2.4 m walls and 0.53 × 10 m rolls: 18 ÷ 0.53 rounds up to 34 strips, each roll gives 4 strips, and 34 ÷ 4 rounds up to 9 rolls, or 10 with the spare.
Each drop has to line up with the pattern of the one beside it, which wastes paper at the top of every strip. A larger pattern repeat wastes more, so one extra roll from the same batch is a common safeguard.
This tool counts full-height strips around the whole perimeter and does not subtract them. The paper saved above a door is usually lost to trimming anyway.
You do not have to open Wallpaper Estimator to use it. Ask Xenition in plain language and it runs the right tool, then carries the answer into whatever you are working on — a document, a spreadsheet, a deck.