Wallpaper Calculator - How Many Rolls Do I Need?

How the wallpaper estimate works

The calculator finds the room perimeter, multiplies it by wall height, and subtracts the standard opening deductions selected for doors and windows. It then divides the resulting wall area into vertical strips based on the roll width. The final roll count is rounded up after the waste percentage is applied, so it is a planning estimate rather than a substitute for a measured cut list.

Pattern repeat and cut-drop length

For straight-match wallpaper, adjacent strips must begin at the same point in the pattern. The calculator first adds the trim allowance to the wall height, then rounds that required length up to a whole pattern-repeat multiple. It does not simply add one full repeat to every drop: an 8-foot wall with a 24-inch repeat is already four complete repeats before trim. Enter the repeat from the roll label and the extra length needed to trim the top and bottom.

Trim allowance and usable strips

Trim allowance defaults to zero because the amount depends on your installation. If you need extra paper above and below the wall, enter that total for each drop. The calculator uses the resulting cut-drop length to determine how many complete strips fit in a roll. Taller walls, large repeats, and extra trim all reduce the number of strips available from each roll.

Straight-match assumption

This estimator models straight-match wallpaper only: each strip starts at the same point in the pattern. Half-drop, offset, random-match, murals, and irregular walls can use materially more paper. Confirm the manufacturer's match type and layout instructions, and increase the waste percentage or request a professional layout for those cases.

Buying tips

Buy all rolls from the same dye lot when possible, check the manufacturer's stated coverage, and round up if the estimate is close. Standard American double rolls are often 20.5 inches wide by 33 feet long, while many European rolls are 52 cm by 10 m, but the roll label is the source of truth for a purchase.