Wallpaper Calculator
$
Rolls Needed2
Wall Area (sq ft)96
Usable per Roll (sq ft)56.0
Estimated Cost$70.00
Buying wallpaper by raw square footage almost always comes up short, because every drop must be trimmed and patterned rolls waste material aligning the design. This calculator works in vertical drops instead: it figures how many full-height strips a roll yields after allowing for the pattern repeat, totals the usable coverage per roll, then divides your wall area by that figure and rounds up to whole rolls.
Formula
drops = floor(rollLen / (wallH + repeat)); rolls = ceil((wallW x wallH) / (drops x rollW x wallH))
- wallW
- Wall width, feet
- wallH
- Wall height, feet
- rollW
- Roll width, feet
- rollLen
- Roll length, feet
- repeat
- Vertical pattern repeat, feet
How it works
- Enter the wall width and height in feet, plus the roll width and roll length and any vertical pattern repeat.
- The tool finds how many full-height drops fit in one roll by dividing roll length by (wall height + pattern repeat) and rounding down, since each drop loses up to one repeat to alignment.
- Usable coverage per roll equals those drops times roll width times wall height; wall area divided by that, rounded up, gives the rolls needed and the cost at your price per roll.
Worked example
A 12 ft wide by 8 ft tall wall, using 1.75 ft wide by 33 ft long rolls with no pattern repeat.
- Drops per roll = floor(33 / 8) = 4 full strips.
- Usable coverage = 4 x 1.75 x 8 = 56 sq ft per roll.
- Wall area = 12 x 8 = 96 sq ft; rolls = ceil(96 / 56) = 2.
2 rolls cover the wall; at $35 a roll that is $70.
Frequently asked questions
- Why does a pattern repeat increase the number of rolls?
- To line up a repeating design across adjacent strips, you trim off up to one full repeat from each drop. That waste means fewer usable strips per roll, so a large repeat can push you into buying an extra roll.
- Should I add extra for windows and doors?
- This estimate treats the wall as a solid rectangle, which is the safe approach. Offcuts above and below openings are usually kept as spares, so do not subtract window and door areas unless they are very large.
- What roll size should I enter?
- Use the dimensions printed on the wallpaper label. A common European roll is about 1.75 ft (0.53 m) wide and 33 ft (10 m) long, but American and designer rolls vary, so check before buying.
- Should I order spare rolls?
- Yes. Buying one extra roll from the same batch protects against mistakes, future repairs, and dye-lot mismatches. Rolls from a different production batch can show subtle color differences.