WeekendCalculator free calculators for weekend projects

Wallpaper Calculator

Add each wall's width and height, pick your roll size, and enter the pattern repeat. Rolls needed update as you type, and doors and windows are subtracted automatically.

Wall width (ft) Wall height (ft)
Roll width
Roll length (ft)
Pattern repeat (in)
Doors
Windows
Total wall area
0
Usable area per roll
0
Rolls needed
0

Add wall dimensions above to see how many rolls to buy.

Method: each strip is cut to your tallest wall's height, rounded up to the next full pattern repeat, then fit into each roll's length. That's a stricter estimate than the flat "25 sq ft per roll" shortcut, and it accounts for repeat waste directly. Doors subtract 15 sq ft each and windows subtract 10 sq ft each from total wall area before rolls are counted.

How to calculate how many rolls of wallpaper you need

Start with total wall area, then subtract openings, then divide by how much of a roll you can actually use once trimming and pattern repeat are accounted for.

total wall area = Σ (wall width × wall height) − (doors × 15) − (windows × 10)
effective strip height = repeat > 0 ? ceil(wall height ÷ repeat) × repeat : wall height strips per roll = floor(roll length ÷ effective strip height) usable area per roll = strips per roll × roll width × wall height ÷ 144
rolls needed = ceil(total wall area ÷ usable area per roll)
Worked example. A room has two walls to paper: 12′ wide × 8′ tall, and 10′ wide × 8′ tall, with 1 door and 2 windows. Total area is (12 × 8) + (10 × 8) = 96 + 80 = 176 sq ft. Subtracting openings: 176 − 15 − (2 × 10) = 141 sq ft net. Using a 20.5 in × 33 ft roll with no pattern repeat, each strip uses the full 96″ wall height, so a roll fits floor(396 ÷ 96) = 4 strips, giving 4 × 20.5 × 96 ÷ 144 = 54.7 sq ft usable per roll. Rolls needed: ceil(141 ÷ 54.7) = 3 rolls. Buy a fourth, from the same dye lot, as a spare.

Wall size to rolls, at 20.5 in × 33 ft, no pattern repeat

Single-wall estimates at an 8′ ceiling height, plain roll, no repeat, no door or window subtraction.

Wall widthWall area (8′ height)Rolls needed
8 ft64 sq ft2
10 ft80 sq ft2
12 ft96 sq ft2
15 ft120 sq ft3
20 ft160 sq ft3
25 ft200 sq ft4
30 ft240 sq ft5

How pattern repeat changes roll coverage

Repeat forces each strip to a longer cut length, rounded up to the next full repeat. On an 8′ wall (96″), a 12 in or 24 in repeat happens to divide evenly into 96, so at this specific height neither one wastes extra paper beyond what a plain roll already loses to leftover trim. A repeat that doesn't divide evenly does cost coverage: an 18 in repeat on the same 8′ wall rounds each strip up to 108″, dropping a roll from 4 usable strips to 3.

Pattern repeatEffective strip heightStrips per rollUsable coverage per roll
0 in96 in454.7 sq ft
12 in96 in454.7 sq ft
24 in96 in454.7 sq ft
18 in108 in341.0 sq ft

Single rolls vs. double rolls

US wallpaper retailers price by the single roll but ship double rolls, one bolt equal to two single rolls joined together. A double roll at 20.5 in × 33 ft is about 56.4 sq ft of paper before any trimming. When you compare prices between brands, confirm whether the quoted price is per single roll or per double roll. A price that looks half as expensive is sometimes just quoting the smaller unit.

Frequently asked questions

Should I buy single rolls or double rolls?

US wallpaper is priced per single roll but almost always shipped as a double roll, one continuous bolt equal to two single rolls. A double roll at 20.5 in × 33 ft covers about 56 sq ft of paper before trimming. When a retailer lists a price per roll, check whether that price is per single roll or per double roll before you total your cost.

What is pattern repeat?

Pattern repeat is the vertical distance, in inches, before a wallpaper's design repeats itself. A repeat of 0 means the pattern has no vertical repeat, like a plain texture or a random pattern. A large repeat, 24 in or more, forces you to cut each strip longer than the wall height so the pattern lines up, which wastes more of the roll.

What's the difference between drop match and straight match?

In a straight match, the pattern lines up at the same height on every strip, so each strip starts at the same point in the repeat. In a drop match, also called an offset match, the pattern shifts up or down by half the repeat on alternating strips. Drop match wastes more paper because you cannot reuse the same starting point on every cut, so manufacturers often recommend buying one extra roll to cover it.

Do I subtract doors and windows from the wall area?

Yes, for anything larger than a small window. This calculator subtracts 15 sq ft per door and 10 sq ft per window from your total wall area, a standard estimating shortcut. For an oversized window or a sliding glass door, measure the opening directly and adjust your total by hand instead of relying on the flat subtraction.

How accurate is the 25 sq ft per roll rule of thumb?

It's a rough floor, not a calculation. A plain single roll at 20.5 in × 33 ft contains about 28 sq ft of paper, and the 25 sq ft figure already assumes some trimming waste with no pattern repeat. Add a repeat and real usable coverage drops further, and it varies with wall height, which is why this calculator works from your actual wall height and repeat instead of one fixed number.

Why enter wall width and height separately instead of just square footage?

Square footage alone doesn't tell you how many strips a wall needs, and strip count is what determines how much of each roll goes to waste. A 20-ft-wide, 4-ft-tall wall and a 4-ft-wide, 20-ft-tall wall both total 80 sq ft, but the tall, narrow wall wastes far more paper per strip. If you only need a general square footage total, not a roll count, the square footage calculator handles that directly.