🧻 Wallpaper Calculator
Enter your room dimensions, wall height, and roll size to find how many rolls of wallpaper to buy — with doors, windows, and pattern waste accounted for.
🧻 Room & Roll Details
What is a Wallpaper Calculator?
It turns a few measurements into the one number you need at the store: how many rolls of wallpaper to buy. From the room perimeter and wall height it computes the wall area, subtracts an allowance for each door and window, adds a waste margin for trimming and pattern matching, and divides by the coverage of a single roll — rounding up so you never come up short mid-wall.
Use it to budget a feature wall or a whole room, avoid the frustration of a dye-lot mismatch on a second trip, and buy a sensible spare for future repairs. The figures are estimates for planning — confirm roll coverage on the label and measure carefully before you order.
❓ Frequently Asked Questions
How does the calculator work out how many rolls I need?
It finds the wall area — the room perimeter (twice the length plus width) times the wall height — then subtracts about 15 square feet for each door or window. It divides that area, plus a waste allowance for pattern matching and trimming (15% by default), by the coverage of one roll, which is the roll width times its length. The result is rounded up to whole rolls, since you buy full rolls.
What roll size should I enter?
Check the roll label. A common standard is a roll about 20.5 inches wide and 33 feet long, which covers roughly 56 square feet, and those are the defaults here. European and specialty rolls differ, so enter the actual width and length printed on your rolls for an accurate count.
Why does it add a waste percentage?
Wallpaper is trimmed at the ceiling and baseboard, and patterned papers must be aligned between strips, which wastes material — often more with a large pattern repeat. The default 15% covers typical trimming and matching. Increase it for bold, large-repeat patterns and decrease it for plain or random-match papers.
Should I buy extra for repairs?
Yes. Buy at least one spare roll and check that every roll shares the same batch (or run) number, since color can shift slightly between print runs. Keeping a matching offcut lets you patch damage later without a visible seam or color mismatch.