Wallpaper Calculator

How to measure the walls

Measure the width of every wall you’re papering and add the widths together to get the room’s perimeter. For a full 12 × 14 ft room, that’s 2 × (12 + 14) = 52 feet of wall. For a single accent wall, the perimeter is just that wall’s width. Then measure the height from baseboard to ceiling, or from chair rail to ceiling if you’re only papering above wainscoting. Most US rooms run 8 feet; measure anyway, because 9-foot ceilings change the math meaningfully and can even change how many strips a roll yields.

Count the openings: a standard interior door is about 21 sq ft, a typical window about 15 sq ft. Note them, and also note your paper’s pattern repeat, which is printed on the label or product page as a measurement like “repeat: 10.5 in.” That single number has more effect on how many rolls you need than most people expect.

Skip the area behind a built-in bookcase or fully tiled section, but paper behind movable furniture; couches move, bare drywall patches don’t.

The formula and what it assumes

First, the area:

Wall area = perimeter × wall height, minus door and window square footage.

The 52-foot perimeter with 8-foot ceilings gives 416 sq ft. One door and two windows take off about 51 sq ft, leaving 365 sq ft to cover.

Then the roll count:

Single rolls = wall area ÷ usable area per roll, rounded up.

The usable area, not the printed area, is the honest divisor. A US single roll contains roughly 28-36 sq ft of paper, but pattern matching eats some of it at the top of every strip. The calculator uses three tiers: 32 sq ft per single roll for paper with no pattern match (textures, plains, random-match grasscloth), 28 sq ft for a small repeat (up to about 12 inches), and 24 sq ft for a large repeat. Our 365 sq ft room with a small-repeat paper needs 365 ÷ 28 = 13.04, so 14 single rolls, which you’d buy as 7 double rolls.

The formula assumes standard ceiling heights and a drop-match or straight-match paper hung vertically. Stairwells, two-story foyers, and very tall repeats (24 inches and up) waste more per strip, so treat the large-repeat tier as a floor, not a ceiling, in those cases. It also assumes you’re subtracting openings; if you’d rather not measure them, skip the subtraction and accept a slightly padded estimate.

Buying tips

In the US, wallpaper is priced per single roll but packaged and sold as double rolls, one continuous bolt with twice the paper. So when the calculator says 13 or 14 single rolls, you’re ordering 7 double rolls. A double roll of standard 20.5-inch-wide paper is typically about 33 feet long, enough for four 8-foot strips; with 9-foot ceilings or a big repeat, that can drop to three strips per bolt, which is exactly why the usable-area tiers exist.

The one rule that outranks everything: buy every roll from the same dye lot, in one order. The run number is printed on each label, and rolls from different print runs can differ visibly in color on the wall. If you underbuy and the lot sells out, you may be repapering a whole wall to hide the seam, so order all of it up front and add a roll if you’re near a boundary.

That extra roll is cheap insurance for another reason: most retailers, including Home Depot, Lowe’s, Spoonflower’s partners, and the major wallpaper houses, accept returns on unopened rolls, generally within 30-90 days with a receipt. Check the policy before ordering, since some online-only and made-to-order papers (peel-and-stick customs especially) are final sale. Keep one roll, or at least the long offcuts, after the job for future repairs behind a picture hook or a doorknob ding.

Material choice matters for where it hangs. Traditional unpasted paper gives the widest pattern selection. Prepasted papers activate with water and suit patient first-timers. Peel-and-stick is the most forgiving to hang and remove, which makes it the rental-friendly pick, but it wants smooth, sound paint underneath and can lift in steamy bathrooms.

Frequently asked questions

What's the difference between a single roll and a double roll?

A single roll is the pricing and estimating unit, about 28-36 sq ft of paper. In the US, wallpaper is almost always packaged and sold as double rolls, one continuous bolt equal to two single rolls. If our calculator says you need 7 single rolls, you'd buy 4 double rolls.

What is pattern repeat and why does it reduce coverage?

The repeat is the vertical distance before a pattern duplicates itself, printed on the label. To align the pattern across strips, you trim paper off the top of each strip, so a roll yields less usable area: figure 32 sq ft per single roll with no match, 28 sq ft for repeats up to about 12 inches, and 24 sq ft for larger repeats.

Why do all my rolls need the same dye lot?

Wallpaper is printed in batches, and ink color shifts slightly between runs. Two rolls from different lots can look fine side by side in your hands and clearly different on a lit wall. The lot or run number is printed on each label; confirm every roll matches before you cut.

Should I subtract doors and windows when estimating wallpaper?

Yes, subtract them from the wall area: about 21 sq ft for a standard door and 15 sq ft for a typical window. But round your final roll count up, not down, since strips around openings still need full-height pattern alignment and generate extra scrap.