Wallpaper Calculator
How many rolls of wallpaper for a room
Hanging wallpaper? Enter the total wall area to estimate how many rolls you need, with extra built in for pattern matching.
How many rolls of wallpaper?
Measure the length of every wall, multiply by ceiling height, and divide by the usable area of a roll. A US single roll yields roughly 25 usable ft² after trimming and pattern matching — noticeably less than the raw area printed on the label, because the trimmed edges and the offcut at the bottom of each drop never reach the wall.
| Wall run × height | Area | 15% waste | 20% | 25% | 30% |
|---|---|---|---|---|---|
| 40 ft × 8 ft | 320 ft² | 15 | 16 | 16 | 17 |
| 48 ft × 8 ft | 384 ft² | 18 | 19 | 20 | 20 |
| 56 ft × 9 ft | 504 ft² | 24 | 25 | 26 | 27 |
| 64 ft × 9 ft | 576 ft² | 27 | 28 | 29 | 30 |
Do not deduct small windows and doors. Wallpaper is hung in full-height drops, so a window in the middle of a wall does not save you a drop — it just means you cut around it and bin the middle. Deduct only a full-height opening such as a wide doorway or an archway.
Pattern repeat is the whole game
A wallpaper repeat calculator and a wallpaper cost calculator both come back to this one number, since wallpaper coverage per roll falls as the repeat grows.
The repeat is the vertical distance before the design starts again, and it is printed on every roll label. It matters because each drop has to begin at the same point in the pattern, so every drop gets cut to the next whole multiple of the repeat.
Drop length = ceiling height + trim allowance, rounded UP to the next whole repeat. The offcut is waste on every single drop.
| Pattern repeat | Cut length per drop | Waste | Set waste to |
|---|---|---|---|
| Plain or random match | 112 in | 0% | 15% |
| 6 in | 114 in | 1.8% | 15% |
| 12 in | 120 in | 7.1% | 20% |
| 18 in | 126 in | 12.5% | 25% |
| 24 in | 120 in | 7.1% | 20% |
Look closely at the last two rows: a 24 inch repeat wastes less than an 18 inch one at this ceiling height, because 112 inches happens to fall just under a clean multiple of 24. Repeat waste is not proportional to repeat size — it depends entirely on how your wall height divides. Work out your own drop length before assuming a big repeat is expensive.
Match type matters too. A straight match lines up level across every drop. A drop match (often labelled half-drop) staggers alternate drops by half a repeat, which usually means less waste overall because the offcut from one drop starts the next. A random match, like most grasscloth and stripes, has effectively no repeat waste at all.
Single roll vs double roll, and why the label lies
Wallpaper is sold in confusing units, and the roll count on its own tells you very little:
| Format | Dimensions | Raw area | Usable area |
|---|---|---|---|
| US single roll | ~27 in × 13.5 ft | ~30 ft² | ~25 ft² |
| US double roll | ~27 in × 27 ft | ~60 ft² | ~50 ft² |
| European roll | 0.53 m × 10.05 m | 57 ft² (5.3 m²) | ~45 ft² |
The trap is that American wallpaper is almost always priced as single rolls but packaged and sold as doubles. If a calculator says you need 18 single rolls, you are buying 9 double rolls. Always order against the square footage on the label rather than the roll count, and check whether the number quoted is the raw or the usable figure.
Buy one batch, and buy one spare
Wallpaper is printed in runs, and colour shifts measurably between them. Every roll carries a batch or lot number and rolls from different batches will not match on the same wall — the difference is invisible in the shop and obvious under daylight at home.
Order everything in one go, and add a spare roll beyond what the calculator says. A single damaged drop three years later cannot be fixed unless you kept some, and the batch will be long gone. Write the batch number somewhere you will find it again.
Hanging it well
- Prime the wall with a wallpaper primer or sizing. It gives even absorption, lets you slide drops into position, and makes eventual removal far less destructive.
- Start from a plumb line, not a corner. No corner in a house is truly vertical, and starting from one puts the error into every drop after it.
- Book pasted paper — fold it paste to paste and leave it a few minutes to relax before hanging, or it will expand on the wall and bubble.
- Work away from the main light source so the seam shadows fall away from view.
- Peel-and-stick is renter-friendly and forgiving on flat, smooth, painted walls, and unforgiving on anything textured.
- Textured walls need skimming first. Wallpaper telegraphs every bump underneath it.
How this wallpaper calculator works out its numbers
Rolls are wall area × (1 + waste) ÷ 25 ft², rounded up, with a 15% default waste allowance. 25 ft² is the usable yield of a US single roll after trimming and matching, not the raw area on the label.
- Pattern repeat is handled through the waste field, not calculated. Use the repeat table to pick a figure: 15% for plain or random match, 20% for a repeat around 12 in, 25% for 18 in and up. The drop-length arithmetic in that table lets you work out your own if you want to be exact.
- Repeat waste is not proportional to repeat size. It depends on how your drop length divides, which is why a 24 in repeat can waste less than an 18 in one.
- No deduction for openings. Paper hangs in full-height drops, so windows and standard doors do not reduce the number of drops. Reduce the length you enter for a full-height opening.
- Results are in US single rolls. Halve the count for double rolls, which is how American paper is usually packaged. European rolls yield roughly 45 usable ft².
- Not included: paste, primer or sizing, and the spare roll you should buy from the same batch.
Reviewed September 2026.
Figures reviewed . Every worked example on this page is checked against the calculator above.
Wallpaper Calculator: frequently asked questions
How much wallpaper do I need?
Multiply total wall length by ceiling height, then divide by about 25 ft² per US single roll and add 15% for a plain paper. A 48 ft × 8 ft run is 384 ft², or 18 single rolls, which is 9 double rolls.
Why does pattern repeat matter?
Every drop must start at the same point in the pattern, so each one is cut to the next whole multiple of the repeat and the offcut is wasted. A 12 inch repeat on a 9 ft ceiling adds about 7% waste, and an 18 inch repeat about 12.5%.
How do I calculate wallpaper with a repeat?
Take your ceiling height plus about 4 inches of trim allowance, then round up to the next whole multiple of the repeat. That is your cut length per drop, and the difference from the plain length is your repeat waste.
Does a bigger pattern repeat always waste more?
No, and this catches people out. It depends on how your drop length divides. At a 112 inch drop, a 24 inch repeat wastes 7.1% while an 18 inch repeat wastes 12.5%, because 112 sits just under a clean multiple of 24.
What is the difference between a single and double roll?
American wallpaper is priced by the single roll of about 25 usable ft² but almost always packaged and sold as double rolls of about 50 ft². If you need 18 single rolls you are buying 9 packages.
Should I subtract windows and doors?
Only full-height openings such as a wide doorway or archway. Wallpaper hangs in full drops, so a window in the middle of a wall does not save you a drop; you cut around it and discard the middle.
Why do I need the same batch number?
Wallpaper colour shifts between print runs. Rolls from different batches look identical in the shop and visibly different on the same wall in daylight. Order it all together and keep a spare roll for future repairs.
How many rolls for an accent wall?
Measure the wall's width times its height, divide by about 25 ft² per single roll and add 15%, or more for a large repeat. A typical 8 ft tall accent wall runs two to four single rolls.