Wallpaper Calculator

Buying wallpaper by guesswork almost always means buying too much. By calculating the exact number of rolls a room needs, accounting for pattern repeats and the openings left by doors and windows, you can trim material spending by an estimated 10-15%. That matters in 2026, when a single roll typically runs $45 to $75, and the leftover rolls you avoid buying also keep waste out of the landfill.

The math starts with total wall area, found by multiplying wall height by the combined width of the walls. The area of every door and window you enter is then subtracted from that figure. Dividing the remaining area by the coverage of one roll yields the roll count, and that coverage already bakes in a 10% allowance for trimming and matching seams, with extra room set aside for the pattern repeat so the design lines up cleanly from strip to strip.

Round the result up to the next full roll every time. Coming up short partway through forces a fresh order, and a new batch can arrive in a slightly different shade. Busy patterns and long repeats eat more material than plain designs, so expect those to push the count higher. Tricky corners, alcoves, and odd cuts also draw down your supply faster than flat walls do.