Wallpaper Calculator
Work out how many wallpaper rolls a room needs, including the pattern repeat that quietly consumes up to a third of every roll before it reaches the wall.
Perimeter × height. Ignore doors and windows — offcuts absorb them.
A US double roll is typically 56–60 sq ft.
Printed on the label. Bigger repeats waste more of every strip to matching.
At this repeat, 25.0% of each roll is lost to pattern matching, so a roll effectively covers 43 sq ft. Buy every roll from the same batch number — dye lots vary, exactly as with tile.
What this calculator does
Wallpaper has a hidden variable that paint does not: the pattern repeat. Two papers with identical coverage printed on the label can need very different roll counts for the same room, because every strip of a patterned paper is cut long so its motif lines up with the strip before it — and the trimmings go in the bin.
This calculator applies the standard derates for repeat size to the nominal coverage, then rounds up to whole rolls, which is the only way wallpaper is sold.
The arithmetic
usable per roll = nominal coverage × derate
rolls = wall area ÷ usable per roll, rounded upThe derates by repeat size:
| Repeat | Usable share of each roll |
|---|---|
| None / random match | 100% |
| Small (up to 6 in) | 85% |
| Medium (7–12 in) | 75% |
| Large (13–24 in) | 65% |
A 320 square foot room in a 57 square foot double roll with a medium repeat: 57 × 0.75 = 42.75 usable square feet per roll, so 8 rolls rather than the 6 the label arithmetic suggests. That two-roll gap is the single most common wallpaper ordering error.
Measuring the room
Perimeter × height, exactly as for paint. A 12 × 14 foot room is 52 feet of perimeter; at 8-foot ceilings that is 416 square feet of wall.
Do not deduct doors and windows. As with drywall, the offcuts created by cutting around an opening roughly cancel the area deducted — and pattern matching makes wallpaper offcuts even less reusable, since a leftover piece must match the repeat where it lands, not just fit the space.
The one legitimate deduction is a wall you are not papering at all. An accent wall is its own small calculation, not a fraction of the room’s.
Single rolls, double rolls, and the pricing trap
US wallpaper is priced by the single roll and sold by the double roll. A double roll covers roughly 56–60 square feet; a single covers half that. Two retailers quoting “$45 a roll” may be quoting different units, making one look half the price of the other for identical paper.
Always convert to price per square foot of usable coverage before comparing — which means applying the repeat derate first. A cheap large-repeat paper can cost more per finished wall than a dearer solid.
Batches, spares and repairs
Wallpaper is printed in runs and colour drifts between them — the same dye-lot problem as tile. Three habits prevent the expensive version of this lesson:
- Buy every roll at once and check the batch numbers on the labels match.
- Buy one spare roll. Patterns are discontinued constantly, and a damaged strip with no matching paper means redoing the wall.
- Store the spare flat and dry, with the label, so the batch is identifiable years later.
Surface preparation is half the job
Wallpaper telegraphs everything underneath it. Fill and sand dents, degloss shiny paint, and prime. A dedicated wallpaper primer-sizer does two jobs: it evens out absorption so the paste dries at one rate, and it makes the paper strippable when its time comes, instead of a scraping job that damages the drywall beneath.
New drywall especially needs sizing — bare paper face and joint compound absorb paste at wildly different rates, the same flashing problem that affects paint on new board. If walls are being repaired first, the drywall calculator sizes that work.
What this leaves out
- Paste, for unpasted papers — roughly a gallon per four to five rolls, though pre-pasted and peel-and-stick papers skip it.
- Tools: a smoother, a seam roller, a sharp snap-blade knife and a level. The level matters most; the first strip sets every strip after it.
- Labour. Hanging patterned paper well is a genuine skill, and papering a stairwell or a ceiling is professional territory.
- Removal of existing paper, which can be quick or can be the worst day of the project — there is no way to know until you start a corner.
If the room is getting paint elsewhere, the paint calculator covers those walls, and how much paint a room needs walks through the same perimeter-times-height measurement used here.
For installation standards and surface preparation guidance, the Wallcoverings Association publishes the references professional installers work from.
How this is calculated
usable per roll = nominal coverage × repeat derate no repeat 100% · small 85% · medium 75% · large 65% rolls = ceiling( wall area ÷ usable per roll )
Frequently asked questions
- What is a pattern repeat and why does it matter?
- The vertical distance before the design repeats itself, printed on the label. Every strip must be cut so its motif aligns with the strip beside it, and the trimmed-off length grows with the repeat. A large repeat can consume a third of each roll before any paper reaches the wall, which is why two papers with identical coverage need different roll counts.
- Should I subtract doors and windows?
- No, for the same reason as drywall and paint. The offcuts created by cutting around an opening roughly cancel the area you would deduct, and pattern matching makes wallpaper offcuts even less reusable than drywall ones. Measure the full perimeter times height and stop there.
- What is the difference between a single and double roll?
- American wallpaper is priced by the single roll but almost always sold in double rolls covering roughly 56 to 60 square feet. Check which unit a price refers to before comparing — a shop quoting singles looks half the price of one quoting doubles for identical paper.
- Why do batch numbers matter?
- Wallpaper is printed in runs, and colour shifts subtly between them — the same dye-lot problem as tile. Buy every roll from one batch, check the numbers on the labels, and buy a spare, because a later batch bought to fix one damaged strip can be visibly different across a whole wall.
- How much does the wall condition matter?
- A great deal. Wallpaper telegraphs every bump beneath it, glossy paint stops paste bonding, and fresh drywall drinks paste unevenly unless sized first. A coat of wallpaper primer-sizer is cheap insurance on any surface and makes the paper strippable later rather than a scraping job.