Wallpaper Calculator
Rolls from the wall, the roll on the label and the pattern repeat, counted in strips because a roll yields whole strips and nothing else.
Rolls from the wall, the roll on the label and the pattern repeat — counted in strips, because a roll yields whole strips and nothing else.
| Wall area | — |
|---|---|
| Strips needed | — |
| Strip length, cut | — |
| Strips per roll | — |
| Rolls | — |
Square feet do not buy wallpaper; strips do. A roll is a fixed width and length, and it yields as many full-height strips as fit along it — three strips of 8 ft 4 in from a 33-foot roll, with a couple of feet left that are good for nothing but a strip above a door. Divide the perimeter by the roll width for the strips, the roll length by the cut strip length for the strips a roll gives, and the rolls are the ratio rounded up. Area-based charts are this arithmetic with a product assumed; the label is better than the assumption.
The repeat makes every strip longer. A pattern that repeats every 25 inches has to line up at the seam, so each strip is cut to a whole number of repeats above the wall height: an 8-foot wall takes four repeats, 100 inches, plus trim. That is why a bold pattern on a 33-foot roll still gives only three strips and the fourth becomes waste. Enter 0 for a random or textured paper.
Openings are not deducted. Doors and windows save part of a strip, not a strip, and the strip is what you buy. On a wall of windows the paper above and below still comes off full strips. The exception is a whole wall of glass, which you can take out of the perimeter yourself.
Single roll, double roll. American paper is priced by the single roll and sold by the double: a 20½ × 33 ft bolt is two “single rolls” of 16½ ft. Enter the bolt you will actually receive; a 16½-foot length gives one 8-foot strip per roll, and the count doubles or worse.
Strips = ceil(perimeter ÷ roll width). Cut length = wall height rounded up to a whole number of repeats, plus the trim allowance. Strips per roll = floor(roll length ÷ cut length). Rolls = ceil(strips ÷ strips per roll). Roll width and length are the label’s figures; 20½ in × 33 ft is a common American double roll and is a default, not a standard.
Worked example
A room with 44 ft of wall, 8 ft high, in 20½ in × 33 ft double rolls: how many rolls?
- Strips: 44 × 12 ÷ 20.5 = 25.8, so 26.
- Each strip is cut 8 ft plus 4 in of trim = 8 ft 4 in; a 33 ft roll yields floor(33 ÷ 8.33) = 3.
- 26 ÷ 3 = 8.7, so 9 rolls, with one spare strip.
9 double rolls. The same wall in 16½ ft single rolls yields one strip a roll and takes 26 — the label's length is the whole answer.
Questions
How many rolls of wallpaper for a room?
Strips first: perimeter ÷ roll width, rounded up. Then strips per roll: roll length ÷ cut strip length, rounded down. Rolls are the ratio rounded up — 9 double rolls for 44 ft of 8-foot wall on 20½ in × 33 ft rolls.
Does the pattern repeat change the count?
Yes: each strip is cut to a whole number of repeats above the wall height, so a 25-inch repeat on an 8-foot wall cuts 100 inches plus trim instead of 96, and a roll yields fewer strips.