Wallpaper Calculator
Tell us the size of your room, the doors and windows, and the roll you plan to buy - we work out exactly how many rolls you need, updated live as you type. It accounts for the pattern repeat that wastes paper on patterned designs, plus a waste allowance and the cost. Everything runs in your browser, nothing uploaded.
Drops Across the Walls
Enter room and roll sizes to see the drop layout
Estimate Breakdown
Learn more: estimating wallpaper rolls
How the roll count is worked out
The calculator measures around the room (the perimeter) and divides by the roll width to get the number of full-height drops. A 4 m by 3 m room has a 14 m perimeter; with a 53 cm wide roll that is 14 / 0.53 = 26.4, rounded up to 27 drops. Each roll is then cut into as many drops as fit in its length: a 10.05 m roll divided by a 2.4 m ceiling gives 4 drops per roll. So 27 drops over 4 drops per roll is 6.75, rounded up to 7 rolls before any waste allowance.
Why pattern repeat costs you extra rolls
Plain or textured paper is a free match - every drop only needs the wall height. Patterned paper has to line up between drops, so each drop is trimmed up to one full repeat. The calculator rounds each drop length up to a whole number of repeats. With a 64 cm repeat and a 2.4 m wall, each drop becomes 2.56 m, so a 10.05 m roll now yields only 3 drops instead of 4. That same 27-drop room jumps from 7 rolls to 9. A drop match (half-drop) offsets alternate drops and wastes an extra half repeat on average, so it lands between straight match and the worst case.
Waste, doors and windows
A waste allowance (10% is a common default) covers trimming, mistakes and keeping a spare drop for future repairs. It is applied to the number of drops before the roll count is rounded. Doors and windows usually do not save whole rolls, because you still paper the short strips above and below them, so the roll count is taken from full-height drops across the whole perimeter. The door and window sizes you enter feed the net wall area, which is handy as a paste-coverage and sanity check rather than for cutting fewer rolls.
FAQ
How does pattern repeat change how many rolls I need?
A pattern repeat forces every drop to start at the same point in the design, so each drop is trimmed up to one full repeat to line up with its neighbour. The calculator rounds each drop length up to a whole number of repeats, which lowers the usable drops per roll. A 64 cm straight-match repeat on a 2.4 m wall makes each drop 2.56 m, so a 10.05 m roll yields 3 drops instead of 4 - meaning more rolls for the same room.
Do doors and windows reduce the number of rolls?
Rarely. Wallpaper hangs in full-height drops, and you still paper the strips above and below a door or window, trimming around the opening. This calculator counts rolls from full-height drops across the whole perimeter, which is the safe approach. The door and window figures feed the net wall area shown alongside, which is useful as a paste-and-coverage cross-check rather than for cutting whole rolls.
What is the difference between straight match and drop match?
Straight match means the pattern lines up horizontally across drops at the same height, so adjacent drops are identical. Drop match (half-drop) shifts every other drop down by half a repeat, creating a diagonal flow, which wastes an extra half repeat per drop on average. Free match has no repeat - textures and plain papers - so each drop only needs the wall height.