Wallpaper Calculator
Enter room dimensions, openings, roll size, and pattern repeat to estimate how many rolls to buy.
Last reviewed: June 2026Room Dimensions
Doors & Windows
Custom opening size (optional)
Enter a non-standard opening and add it to the deduction. Leave at zero to skip.
Roll Specifications
About the Wallpaper Calculator
This wallpaper calculator estimates how many rolls to buy for one rectangular room. It uses room length, room width, ceiling height, the number of standard doors and windows, optional custom openings, roll width, roll length, pattern repeat, and optional cost per roll. The output is an estimating target, not a promise that every wall will install without extra waste.
The wall area formula is straightforward: total wall area = 2 x (room length + room width) x ceiling height. The calculator then subtracts partial opening deductions. A standard 3x7 door is deducted at 80% of its area, a standard 3x4 window is deducted at 50%, and custom openings are deducted at 65%. Those partial deductions reflect a common jobsite reality: strips often still run around openings, and offcuts are not always reusable.
Roll Coverage and Pattern Repeat
Roll coverage is not just roll width x roll length. Wallpaper is installed in vertical strips, so the calculator first converts roll width from inches to feet and then calculates how many full-height strips fit into one roll. With no pattern repeat, strip length equals ceiling height. With a pattern repeat, each strip is rounded up to the next full repeat before the strips-per-roll calculation runs. That can reduce usable coverage quickly on tall rooms or large-repeat papers.
For the default 12 ft by 10 ft room with 8 ft ceilings, one standard door, two standard windows, a 20.5 inch by 33 ft roll, and no repeat, the total wall area is 352.0 sq ft. The partial opening deduction is 28.8 sq ft, leaving 323.2 sq ft of net coverage. Each roll yields four 8 ft strips, or about 54.7 sq ft of usable coverage, so the result rounds 5.91 calculated rolls up to 6 rolls.
Practical Buying Notes
Always round up. Wallpaper lots can vary in color, and returning later for one extra roll may leave you with a different dye lot. Add a manual cushion when the room has many corners, sloped ceilings, built-ins, damaged walls, a large pattern repeat, or a layout where you want pattern centering above a focal wall. The calculator's waste percentage reports the extra usable area from the rounded roll count; it is not a complete installer waste allowance.
The optional cost-per-roll input multiplies the roll count by the material price only. It does not include paste, primer, smoothing compound, tools, tax, shipping, waste preference, removal of old wallpaper, wall repair, or labor. For multiple rooms, run the calculator once per room and keep each room's roll count separate before adding totals.