Wallpaper Calculator
Avoid buying too much or too little wallpaper. Enter your room dimensions, number of doors and windows, and roll specifications to get an accurate roll count. The calculator accounts for trimming waste and standard opening sizes.
The calculator first determines the total wall area by multiplying the room perimeter (2 x length + 2 x width) by the ceiling height. It then subtracts approximately 21 square feet per door and 15 square feet per window to get the usable wall area that needs covering.
Each wallpaper roll is then analyzed for how many full-height strips can be cut from it (based on ceiling height plus a half-foot trim allowance per strip). The usable area divided by the effective coverage per roll gives the number of rolls needed, rounded up.
For patterned wallpaper with a repeating design, you may need 15-20% more material to align the pattern at seams. Consider ordering one extra roll beyond the calculated amount to have on hand for future repairs or mistakes during installation.