Wallpaper Roll Count Calculator
Count the wallpaper rolls a room needs by matching strips to the roll length, allowing for ceiling height and the pattern repeat.
How it works
Strips per roll = ⌊roll length ÷ (wall height + pattern repeat)⌋ · Strips needed = ⌈wall width ÷ roll width⌉ · Rolls = ⌈strips needed ÷ strips per roll⌉
Wallpaper is hung in vertical strips cut to the wall height, so the real question is how many full-height strips one roll yields and how many strips the walls require. A pattern repeat wastes length because every strip must start at the same point in the design, effectively adding one repeat to each cut. Rounding up at both stages — strips per roll down, rolls up — prevents running short mid-wall, and a spare roll guards against dye-lot changes.
Worked example
A room with 40 ft of wall at 8 ft high needs ⌈480 in ÷ 20.5 in⌉ = 24 strips. A 33 ft roll is 396 in, and with no repeat each 96 in strip means ⌊396 ÷ 96⌋ = 4 strips per roll, so you need ⌈24 ÷ 4⌉ = 6 rolls — buy 7 to be safe.
Frequently asked questions
How many rolls of wallpaper do I need?
Work out how many full-height strips your walls need (wall width ÷ roll width) and how many strips one roll yields (roll length ÷ strip height), then divide. Always round up and add a spare roll, because a later roll may not match the dye lot.
How does the pattern repeat change things?
With a repeat, every strip must begin at the same point in the design, so you effectively waste up to one repeat per strip. A large repeat can cut the strips you get from a roll, meaning more rolls for the same wall.
Should I subtract doors and windows?
For a rough count it is safest not to, since the offcuts around openings are rarely reusable and the extra becomes your spare. For big openings like patio doors you can deduct roughly a strip or two, but keep a margin.
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This calculator is for educational purposes. Double-check important results before acting on them.