Walls
Wallpaper calculator
Every wallpaper calculator works out the area and divides by the coverage on the roll. A roll does not cover area — it yields whole strips, and whatever is left at the end papers nothing. Which is why the same paper on the same wall is 10 rolls as a straight match and 14 as a half-drop, why a 36 inch repeat can cost less than a 21 inch one, and why two inches of ceiling can change the order by a fifth. This works in strips and never converts to square feet.
Written and edited by Pablo Ruiz Quintero
Last reviewed 2026-09-22 · Nothing you type leaves your browser
Paper is not sold by the square foot
A roll yields whole strips, and how many depends on the pattern rather than the area. This never converts to square feet, which is exactly why it comes out right.
Add up the walls you are papering. For a whole room, all four; for a feature wall, just that one.
At its TALLEST point. Every strip is cut for the tallest part of the wall, so that is the number that matters — and old houses are rarely level.
Total area not papered. It reduces the paper on the wall but barely reduces the strips, because a window still needs paper above and below it.
Openings that run floor to ceiling, which genuinely remove whole strips.
The pattern
Both of these are printed on the back of the sample, and almost nobody reads them. They decide the order more than the area does.
The pattern repeats at the same height on every strip, so each one is cut to the next whole repeat above the wall. The offcut is what is left of that repeat.
Each strip is cut to the next whole repeat above 8.5 ft plus 4 in of trim — 10.5 ft here.
The paper
The commonest American format. It is sold as one bolt and priced as one, even though the trade still quotes coverage in single rolls — which is the other reliable way to order half of what you need.
Paste-the-wall rather than paste-the-paper, which makes hanging faster and stripping much easier later. It is the grade where a pattern repeat starts getting large.
Worth it on an imperfect wall or under a heavy paper.
Nothing to remove, or somebody else is doing it.
Priced by the strip, which is how hangers actually quote.
Used only to pick a regional labour rate. It stays in your browser.
Non-woven or designer · straight match
10 rolls
3 strips a roll at 10.5 ft · 28 strips to hang · $2,812
564 ft² of paper for 348 ft² of wall
Of that gap, 20 per cent is the pattern itself — the end of each roll, too short for another whole strip. The rest is windows and the last part-roll. This is why buying by the square foot comes out short every time.
This is a cliff, not a slope
20 inches taller and it is 2 strips a roll
At 8.5 ft a roll gives 3 strips. At 10.17 ft it gives 2, and the order jumps by about 50 per cent for a wall that is barely different.
Measure at the tallest point, because every strip has to be cut for it. An old ceiling that runs out by two inches can cost a fifth of the paper.
The same paper, three matches
Same repeat, same wall. The match type is doing the work.
| Match | Cut | A roll | Rolls | Waste |
|---|---|---|---|---|
| Random | 8.83 ft | 3 | 10 | 20% |
| Straight · yours | 10.5 ft | 3 | 10 | 20% |
| Half-drop | 11.38 ft | 2 | 14 | 46% |
Where the steps are
Rolls against wall height, for this paper.
What to order
- Non-woven or designer, American double roll
3 full strips from each roll at 10.5 ft a strip, and 28 strips to hang. Paste-the-wall rather than paste-the-paper, which makes hanging faster and stripping much easier later. It is the grade where a pattern repeat starts getting large.10 rolls - Sizing
A coat that seals a porous wall so the paste does not soak straight into it. On new plaster it is not optional.$38 - Hanging, 28 strips
Priced by the strip rather than by area, and a straight match takes longer than a plain one for the same wall.$1,474
What it costs
National average. 10 rolls of non-woven or designer and 28 strips hung. Not included: making good the wall, painting woodwork, or a second dye lot if this one runs short.
Order it all at once and check the dye lot on every roll before starting — paper is printed in batches and two batches are reliably slightly different colours, which is invisible in the shop and obvious on a wall.
Worth knowing
- Paper is not bought by the square foot and this page never converts to it. A roll yields whole strips: this one gives 3 at 10.5 ft each, the walls need 28 strips, so the order is 10 rolls. The 564 ft² that buys against 348 ft² of wall is a consequence, not a method — and it is why every square-foot estimate comes out short. Of the difference, 20 per cent is the pattern itself, cut off the end of each roll; the rest is windows and the last part-roll.
- The same paper on the same wall: 10 rolls as a random match, 10 as a straight match and 14 as a half-drop. The match type is doing more here than the size of the repeat is, and it is printed on the back of the sample in letters most people never read.
- This is a cliff, not a slope. At 8.5 ft a roll gives 3 strips; at 10.17 ft it gives 2, and the order jumps by about 50 per cent. 1.67 ft of ceiling is the whole difference. Measure the wall at its tallest point before ordering, because the tallest point is what every strip has to be cut for.
- A bigger repeat is not automatically worse. What matters is where it lands against your wall height, not how large it is — a 36 in repeat can fall exactly right and cost no more than a plain paper, while a 21 in one on the wrong ceiling loses a strip from every roll. Ask the supplier for the repeat and the match before choosing, and put your wall height next to them.
- Order the whole job at once and check the dye lot on every roll before hanging. Paper is printed in batches and two batches of the same pattern are reliably slightly different colours — which is invisible in the shop and obvious on a wall. Running short halfway is the commonest way a room ends up with a seam you can see from the door.
- Hanging is priced by the strip rather than by the square foot, which is why a tall room costs more than its area suggests and a half-drop costs more than a random match for the same wall. 28 strips at a straight match works out around $1,474.
On this page — 3 sections
A roll does not yield area. It yields strips.
The short version
- 10 rolls as a straight match, 14 as a half-drop — same paper, same wall.
- A roll gives 3 whole strips and the rest is too short to use. There is nothing in between.
- A bigger repeat is not automatically worse. What matters is where it lands against your ceiling.
- The waste is a cliff. Two inches of ceiling can change the order by a fifth.
Every wallpaper calculator does the same thing: works out the wall area, divides by the coverage printed on the roll, adds ten per cent, and hands you a number. It is a reasonable-looking method and it is structurally wrong.
A roll of wallpaper does not cover area. It produces whole strips, floor to ceiling, and whatever is left at the end of the roll papers nothing at all. This roll is 33 ft long; each strip has to be 10.5 ft; so it gives 3 strips and .14 of a strip that goes in the bin.
Converting to square feet quietly assumes that offcut is usable. It is not — and that assumption is precisely the gap between what the calculator says and what the shop has to sell you.
| Wall height, plus trim | 8.5 ft + 4 in |
| Rounded up to a whole 21 in repeat | 10.5 ft a strip |
| Roll length | 33 ft |
| Whole strips from a roll | 3 |
| Strips the walls need | 28 |
| The order | 10 rolls |
No square foot appears anywhere in that sequence, and that is deliberate. The 564 ft² it buys against 348 ft² of wall is a consequence of the arithmetic, never a route to it.
Wallcoverings Association, and ASTM F793, Wallcovering roll formats, pattern match types and hanging allowances · checked 2026-09-22
The waste is a cliff, not a slope
Everybody assumes the pattern repeat works like a tax: bigger repeat, more waste, smoothly. It does not. It works like a step.
While the cut length stays under the point where a roll gives one fewer strip, the repeat costs you nothing at all. Cross it and the order jumps by a third or a half in a single move. Which produces two conclusions that sound wrong and are not.
| Repeat, straight match | Cut length | Strips a roll | Rolls |
|---|---|---|---|
| No pattern | 8.83 ft | 3 | 10 |
| 10.5 in | 9.63 ft | 3 | 10 |
| 16 in | 9.33 ft | 3 | 10 |
| 21 in | 10.5 ft | 3 | 10 |
| 25 in | 10.42 ft | 3 | 10 |
| 32 in | 10.67 ft | 3 | 10 |
| 36 in | 9 ft | 3 | 10 |
On a 8.5 ft wall. Note the 36 in repeat: a longer pattern than any of the others and a shorter cut length, because 36 goes into the wall height neatly and 21 does not.
| Straight match | Half-drop match | |
|---|---|---|
| Cut length a strip | 10.5 ft | 11.38 ft |
| Strips from a roll | 3 | 2 |
| Rolls for this room | 10 | 14 |
| Waste within the roll | 20% | 46% |
| Paper cost | $1,300 | $1,820 |
| Hanging | Faster | Slower, and it shows in the quote |
10 rolls
Straight match
3 strips a roll
14 rolls
Half-drop, same repeat
2 strips a roll
20%
Waste from the pattern
Before windows and rounding
14 rolls
At 10.5 ft instead
Two feet of ceiling
MaterialsEstimator, Wallpaper and hanging price survey · checked 2026-09-22
What goes wrong
01Working it out by the square foot
A roll yields whole strips and the offcut papers nothing. On this wall 20 per cent of each roll is unusable before windows are even considered.
Instead — Work in strips: cut length, strips per roll, strips needed, divide. The area is a result, not a method.
02Not reading the match type off the sample
The same 21 in repeat is 10 rolls as a straight match and 14 as a half-drop. It is printed on the back and it is the single most consequential thing there.
Instead — Read both the repeat and the match before choosing, and put your wall height beside them.
03Assuming a bigger repeat is worse
It is where the repeat lands against your ceiling that costs, not its size. A 36 in repeat here gives a shorter cut length than a 21 in one.
Instead — Check the specific combination rather than avoiding large patterns on principle. Sometimes the dramatic paper is the cheap one.
04Measuring the wall at a convenient point
Every strip is cut for the tallest part of the wall. In an old house the difference across a room is often two or three inches, and it can cost a fifth of the paper.
Instead — Measure at several points and use the largest. It is the only measurement on this page that cannot be recovered later.
05Confusing single-roll coverage with the double roll you buy
Coverage is often published per single roll while the bolt on the shelf is a double. Reading one and ordering the other halves the order.
Instead — Confirm what the roll actually measures — 20.5 in by 33 ft is the American standard — and work from that.
06Ordering in stages
Paper is printed in batches and two batches are reliably slightly different in colour. It is invisible in the shop and obvious on a wall, usually from the doorway.
Instead — Order the whole job at once, check the dye lot number on every roll before hanging, and buy the spare now rather than later.
07Dropping the lining paper to save money
It is what makes a heavy or delicate paper sit flat on a wall that is not perfect, and it is a small fraction of the paper going over it.
Instead — Keep it on an imperfect wall or under an expensive paper. It is the cheapest insurance on the job and the first thing a thin quote removes.
08Accepting hanging quoted by the square foot
A hanger's day is measured in strips, and a half-drop takes visibly longer than a random match for the same wall. Area does not describe either.
Instead — Ask for a price per strip — about $53 here — so a tall room and a difficult match are priced for what they are.
Off the back of the sample, before ordering
- The pattern repeat, in inches. It decides the cut length.
- The match type — random, straight or half-drop. It often matters more than the repeat.
- The roll dimensions, and whether the coverage quoted is per single or per double roll.
- Whether it is paste-the-wall or paste-the-paper, which changes both the hanging and the stripping years later.
- The dye lot, on every roll, before a single one is opened.
- Whether the supplier will cut to your wall height. Some digital and mural papers will, and it removes this whole problem.
- Whether it is washable, and whether that matters in the room it is going in.
- How much extra a matching spare roll costs now against ordering one later, which is to say against not being able to.
- 01Measure the perimeter of what you are paperingAdd the wall lengths. For a feature wall, just that one.
- 02Measure the height at its tallest pointEvery strip is cut for the tallest part of the wall, so that is the number that matters. Old ceilings are rarely level.
- 03Read the repeat and the match off the sampleBoth are printed on the back. They decide the order more than the area does, and almost nobody looks.
- 04Work out the cut lengthWall height plus about 4 inches of trim, rounded up to a whole repeat. A half-drop adds another half repeat.
- 05Divide the roll length by the cut lengthRound down. That is how many whole strips a roll gives, and there is nothing in between.
- 06Count the strips the walls needPerimeter divided by roll width, rounded up, minus any full-height doorways.
- 07Divide and round upStrips needed over strips per roll. That is the order, and no square foot has appeared anywhere.
- 08Order it all at once and check the dye lotTwo batches of the same pattern are different colours. Running short halfway is how a room ends up with a visible seam.
Paper is bought in strips, but paint, plaster and almost everything else on a wall genuinely is bought by area — and that measurement has its own traps, chiefly that nobody deducts the openings consistently.
If it is the wall area you need- Pattern repeat
- The vertical distance before the design starts again, printed on the back of every sample. Each strip has to be cut to a whole number of repeats, which is where the waste comes from.
- Straight match
- The pattern repeats at the same height on every strip, so neighbouring strips line up level. Each strip is cut to the next whole repeat above the wall.
- Half-drop match
- Alternate strips start half a repeat lower, which is what makes a diagonal motif work. It costs an extra half repeat on every other strip and is frequently the difference between three strips from a roll and two.
- Random match
- Textures, grasscloths and many stripes, where nothing has to line up. Every strip is cut the same length and the only waste is the trim.
- Cut length
- What each strip is actually cut to: the wall height plus about 4 inches of trim, rounded up to a whole repeat. It is the number that decides how many strips come out of a roll.
- Double roll
- The bolt wallpaper is actually sold in — typically 20.5 in by 33 ft in America. Coverage is still often quoted in single rolls, which is a reliable way to order half of what you need.
- Dye lot
- The batch a roll was printed in. Two batches of the same pattern are reliably slightly different in colour — invisible in the shop, obvious on a wall.
- Lining paper
- A plain paper hung horizontally first, to give a uniform surface. It is what makes a heavy or delicate paper sit flat on an imperfect wall.
- Sizing
- A coat that seals a porous wall so paste does not soak straight into it. On new plaster it is not optional.
- Non-woven
- A paper hung by pasting the wall rather than the paper. Faster to hang, and it usually strips off dry in whole sheets years later.
- Strip
- One floor-to-ceiling length of paper. It is the unit a roll yields, the unit a hanger prices by, and the unit this calculator works in.
- Drop
- Another word for a strip, and also the word in 'half-drop' — where it means the vertical offset between neighbouring strips rather than the strip itself.
Common questions
- How much wallpaper do I need for a 12 × 12 room?
- With 8.5 ft walls, one door and a couple of windows: 10 double rolls for a straight match with a 21 in repeat, 10 for a random match, and 14 for a half-drop of the same repeat. That is the honest answer — the room does not have one number, because the pattern is half of the question.
- Why can't I just work out the square footage?
- Because a roll does not yield area, it yields whole strips. This one gives 3 strips at 10.5 ft each and the rest of the roll is too short to use — 20 per cent of it, before windows and rounding. Converting to square feet quietly assumes you can use the offcut, and you cannot, which is why area-based estimates come out short.
- How does the pattern repeat affect how much I need?
- Each strip has to be cut to a whole number of repeats, so the cut length jumps to the next multiple above your wall height. On this wall a 21 in repeat makes each strip 10.5 ft instead of 8.83 ft. What matters is not how big the repeat is but where it lands: it only costs you a roll when it pushes the cut length past the point where a roll gives one fewer strip.
- Is a bigger pattern repeat always worse?
- No, and this surprises people. A 36 in repeat on this wall gives a cut length of 9 ft and needs 10 rolls — the same as the 21 in repeat, and in fact a shorter cut. A large repeat that falls neatly against your ceiling height costs nothing extra; a small one that falls badly costs a strip from every roll. Ask for the repeat, then put your wall height next to it.
- What is the difference between a straight match and a half-drop?
- On a straight match the pattern lines up level across neighbouring strips. On a half-drop, alternate strips start half a repeat lower, which is what makes a diagonal motif read properly — and it costs half a repeat on every other strip. On this wall that is the difference between 10 rolls and 14: 40 per cent more paper for a pattern that looks much the same on the wall.
- How much does wallpaper installation cost?
- Hanging is priced by the strip, not by the square foot — around $53 a strip here, so $1,474 for 28 strips. With non-woven or designer paper at $130 a roll the whole room comes to about $2,812, or $1,300 hanging it yourself. A difficult match adds time that area does not describe, which is why per-square-foot quotes drift on tall rooms.
- Does ceiling height really change the order that much?
- It can change it by a fifth in two inches. At 8.5 ft this paper gives 3 strips a roll; at 10.5 ft it gives 2, and the order goes from 10 rolls to 14. Measure at the tallest point of the wall, because that is what every strip has to be cut for — and in an old house the difference from one end of a room to the other is often more than you would guess.
- What is a double roll and why does it matter?
- It is the bolt the paper actually comes in — 20.5 in wide by 33 ft long in America. It matters because coverage is still often quoted per single roll while the thing you buy is a double, so reading one and ordering the other is a reliable way to end up with half what you need.
- Should I order extra?
- The rounding up to whole rolls usually is the extra, and it is normally enough. What matters more is ordering the whole job in one go: paper is printed in batches, two batches are reliably slightly different colours, and topping up later means a seam you can see from the doorway. If you want a spare roll for future repairs, buy it now rather than later.
- Do I need lining paper?
- On a smooth, sound wall with a mid-weight paper, no. On an imperfect wall, under a heavy or delicate paper, or over anything previously painted in a gloss, yes — it is what makes the finish paper sit flat, and it is cheap against the paper going over it. It is also the first thing dropped from a quote to make a price look better.
- How many strips can I get from a roll?
- Roll length divided by cut length, rounded down — 3 here, from 33 ft divided by 10.5 ft. The rounding down is the whole point: 3.14 strips fit mathematically and 3 come out in practice, because two thirds of a strip papers nothing.
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About the author
Pablo Ruiz Quintero — Editor
Editor of MaterialsEstimator. Decides which documents count as a source, what every default value is, and where the line sits between what the reader parses and what the engines compute.
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