A wallpaper calculator estimates how many rolls a room needs from wall dimensions, roll size, pattern repeat, openings, and waste. This strip-based calculator accounts for full-height cuts, so it is more useful than dividing wall area by roll coverage alone.
9 wallpaper rolls provide 26 planned strips with 10% waste.
Wall area
352 sq ft
1 room before openings
Net wallpaper area
301 sq ft
1 door and 2 windows removed
Strips to hang
26
23 strips plus 10% waste
Cut length per strip
100 in
Includes 4 inches for trimming
Enter the room length, width, wall height, and number of matching rooms you plan to wallpaper.
Add the number of standard doors and windows so the estimate can reduce the net wallpaper area.
Enter the roll width and length printed by the manufacturer, or choose a common roll preset.
Use the vertical repeat from the label so each strip is rounded up to a compatible pattern length.
Use the rounded roll count, keep the waste allowance, and buy rolls from the same dye lot.
Measure the wall area, subtract large openings, convert the remaining width into full-height strips, account for pattern repeat and waste, then divide by the usable strips per roll and round up.
A common packaged roll is about 20.5 inches wide by 33 feet long, or roughly 56 square feet. Retailers may use single-roll or double-roll equivalents, so always enter the dimensions printed on the package.
A vertical pattern repeat forces every strip to start at a compatible point. That increases cut length and can reduce how many full-height strips fit on each roll.
Subtract standard doors and windows for a planning estimate, but keep at least 10% waste because material around openings still needs trimming and pattern matching.
Ten percent extra is a practical minimum for simple rooms. Use 15% or more for large repeats, angled walls, difficult layouts, or when you want spare material for future repairs.
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