Wallpaper Calculator

Enter your room or walls, the wall height, the roll size and the pattern repeat, and get the rolls to buy counted the way paperhangers count them: full-height strips per roll, with the square-foot estimate shown beside it so you can see the difference.

Whole room Wall by wall

Room length (ft)

Room width (ft)

Wall 1 width (ft)

Wall 2 width (ft) (optional)

Wall 3 width (ft) (optional)

Wall 4 width (ft) (optional)

Wall height (ft) (floor to ceiling; 8 ft 1 in is 8.08)

Roll size

Roll width (in)

Roll length (ft)

Random match (no repeat) Straight match Drop match

Pattern repeat (in) (printed on the roll label)

Doors

Windows

Door width (in) (blank = 36)

Door height (in) (blank = 84, door and trim)

Window width (in) (blank = 36)

Window height (in) (blank = 60)

Trim allowance per strip (in) (blank = 4: 2 at the top and 2 at the bottom)

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How the wallpaper calculator works

Wallpaper goes up in full-height strips, and that one fact decides how much you buy. A roll is not a pile of square feet you can spread around; it is a long ribbon you cut into strips as tall as your wall plus a little extra to trim at the ceiling and floor. Whatever is left at the end of the roll, if it is too short to make another full strip, never becomes a strip. So the honest way to count is the way paperhangers count: how many strips your walls need, how many whole strips each roll gives, and how many rolls that takes.

A pattern adds one more rule. With a straight match every strip has to start at the same point in the design so the motifs line up across the seams, which means rounding each strip up to the next whole repeat. With a drop match the neighboring strips start half a repeat apart. The calculator cuts your strips from each roll in turn, both ways, and shows you the waste in inches.

The formula

strips = wall width ÷ roll width, rounded up
strip length = wall height + trim (straight match: rounded up to the next repeat)
strips per roll = the whole strips that fit in one roll
rolls = strips ÷ strips per roll, rounded up

Measure around the room for the wall width, or wall by wall for walls that do not meet. The trim is 2 inches at the top and 2 at the bottom, as Brewster's measuring guide suggests, and the repeat is the pattern's vertical repeat from the roll label. Each door and window replaces the full strips it is wide enough to swallow, and the short pieces above and below it come out of what is left at the end of the rolls.

Worked example

A 14 by 12 ft room with 8 ft walls, one door and two windows, papered from standard double rolls (20.5 in by 33 ft) with a straight match and a 21 in repeat. Around the room is 52 ft, or 624 in, which is 30.44 strip widths: 31 strips. The door and each window replace one full strip, so 28 strips.

Each strip is 96 in of wall plus 4 in of trim, 100 in, and a 21 in repeat rounds that up to 105 in of roll. A 396 in roll holds 3 strips with 86 in left over, so 28 strips need 9.33 rolls: 10 rolls.

Now the square-foot way: 416 sq ft of wall minus 51 sq ft of openings is 365 sq ft, and 365 divided by the roll's 56.38 sq ft is 6.47, which rounds up to 7 rolls. That is three rolls short, 30 percent of the order, on a perfectly ordinary bedroom.

The 8 ft wall and the 33 ft roll

Here is what surprised us. On an 8 ft wall, the repeat was not what cost those three rolls. A 33 ft roll is 396 inches, and a strip for an 8 ft wall with 4 inches of trim is 100 inches, so each roll gives three strips and has 96 inches left over: a perfectly good 8 ft length of paper, four inches too short to hang. That leftover is the gap between the square feet on the label and the strips on your wall, and it is there with no pattern at all. A 12 by 12 room with 8 ft walls and a random-match paper takes 29 strips, which is 10 rolls; wall area divided by roll area says 7.

Those leftovers are not wasted if you plan for them: they are where the short pieces over doors and windows come from, which is exactly how the calculator uses them. And they explain a near miss worth knowing about. With 3 inches of trim instead of 4, each strip is 99 inches and a roll gives four of them, so that same room takes 8 rolls. The calculator flags this whenever a trim of up to 2 inches less would add a strip to every roll, because few ceilings and floors are level enough to make shaving the trim safe, and the choice is yours.

So which question is the square-foot method answering? It is the right answer to "how much paper ends up on the wall", and the makers who describe it also tell you to allow extra for the repeat and the trimming. The strip count is how you find out how much extra, on your wall.

Big repeats: it is how the repeat fits, not how big it is

A large repeat can cost a whole strip on every roll, but only when it lands badly against your wall height. Take the same 14 by 12 room with 10 ft walls: 124 inch strips. A 24 inch straight repeat rounds each strip up to 144 inches, so a roll gives only 2 strips and the room takes 14 rolls. A bigger 27 inch repeat rounds each strip to 135 inches, three still fit, and the room takes 11 rolls. The square-foot method says 9 for both. A drop match with the same 24 inch repeat also gets 3 strips from each roll, because starting every other strip half a repeat down happens to waste less at that height. Makers' guides say to allow more for a drop match, which is sensible when you do not know the wall; once you do, the calculator's table shows your wall at every common repeat.

Buy every roll from the same batch

Every roll label carries a batch number, also called the run or dye lot number. Wallpaper is printed in runs, and each run is printed with its own mix of ink, so rolls from two different runs can differ in shade by just enough to show at a seam where they meet on a wall. Order all your rolls at once, check that the numbers match before you open any of them, and if you ever need more later, ask for the same batch. Farrow and Ball suggest adding one more roll to whatever you estimate, for trimming and mistakes, and a spare from the same batch is the only repair patch that will ever match exactly.

Double rolls, single rolls and the European roll

In the US, wallpaper is often priced by the single roll but sold only in double rolls, also called bolts: one continuous roll twice as long, typically 20.5 inches by 33 feet. That double roll is almost exactly the European standard roll, 53 cm by 10 m, so a double roll in Chicago and a roll in London hang about the same wall. Peel and stick rolls are usually the single length, 20.5 inches by 16.5 feet, which on an 8 ft wall means one strip per roll at 4 inches of trim or two at 3 inches. If you are painting the other walls, our paint calculator handles those, and the drywall calculator covers the walls underneath.

Sources

Where the numbers on this page come from. We go to the body that publishes the figure, not to another calculator. See how we verify.

How to Measure and Cut Wallpaper, Brewster Home Fashions. Add 4 in to the wall height for each strip, 2 in at the top and 2 in at the bottom for trimming: our default trim allowance.
Wallpaper Calculator, Brewster Home Fashions. One bolt is 56 sq ft, 20.5 in by 33 ft, the standard double roll; make sure the dye lot number is the same on every roll, and larger repeats need more rolls.
Wallpaper Glossary and Terms, Brewster Home Fashions. A bolt is a double roll, one continuous roll the length of two single rolls, and single rolls are not typically sold; the definitions of straight match, drop match, random match, repeat, and run or dye-lot number.
Frequently Asked Questions, Tempaper and Co.. Double rolls of 20.5 in by 11 yards (56.4 sq ft) and 27 in by 9 yards (60.8 sq ft), single peel and stick rolls of 20.5 in by 16.5 ft (28.2 sq ft), and the advice to request the same lot number for any later order.
Calculating Wallpaper Quantities, Farrow and Ball. Every roll is 10 m long and 53 cm wide (our European roll); quantities are estimated in drops per roll, fewer for larger repeats; and add one more roll, because pattern and color can differ slightly between batches.
Wallpaper FAQs, Graham and Brown. Pattern repeats run from about 1 in to 25 in; the longer the repeat, the less usable yield per roll; a half-drop match repeats at the ceiling line on every other strip; and the area method, with extra allowed for the repeat and trimming.

Frequently asked questions

How do you calculate how many rolls of wallpaper you need?

Count strips, not square feet. Divide the width of the walls by the roll width and round up to get the strips. Add about 4 in of trim to the wall height for the length of each strip, rounded up to the next pattern repeat for a straight match. See how many whole strips fit in one roll, then divide the strips by that number and round up. A 14 by 12 ft room with 8 ft walls, a door, two windows and a 21 in repeat needs 28 strips at 3 per roll: 10 standard double rolls.

How many rolls of wallpaper do I need for a 12x12 room?

With 8 ft walls and standard 20.5 in by 33 ft double rolls, about 10. The room is 48 ft around, which is 29 strips, and each roll gives 3 full-height strips with 4 in of trim, leaving 96 in over that is just too short for a fourth. Dividing the 384 sq ft of wall by the roll's 56.4 sq ft says 7, which is why so many people run short. Doors and windows save a strip or so each.

How does the pattern repeat affect how much wallpaper I need?

The repeat is the vertical distance before the design starts over, printed on the label in inches. With a straight match every strip must start at the same point in the design, so each strip is rounded up to the next whole repeat and the rest is trimmed away. How much that costs depends on how the repeat fits your wall: on a 10 ft wall a 24 in repeat leaves room for only 2 strips per 33 ft roll, while a 27 in repeat still fits 3.

What is the difference between a straight match and a drop match?

In a straight match the design lines up straight across at the ceiling on every strip, so the motifs run in horizontal rows. In a drop match (usually a half drop) the design lines up with every other strip, and neighboring strips start half a repeat apart, so the motifs run on a diagonal. A drop match is often said to need more paper; cut in turn from one roll, it can go either way depending on your wall height.

What is a double roll of wallpaper?

It is one continuous roll twice the length of a single roll, and in the US it is how most wallpaper is actually sold, even when the price is quoted per single roll. The standard double roll is 20.5 in wide by 33 ft long, about 56 sq ft, and there is a wide version at 27 in by 27 ft. The European standard roll, 53 cm by 10 m, is almost the same size as a US double roll.

Why do all my wallpaper rolls need the same batch number?

Wallpaper is printed in runs, and each run is printed with its own mix of ink, so rolls from different runs can differ in shade enough to show at a seam. The batch number on the label, also called the run or dye lot number, tells you which run a roll came from. Buy every roll in one order, check that the numbers match before opening any, and ask for the same batch if you ever reorder.

How much extra wallpaper should I buy?

Count strips per roll first, since that already includes the trim and the repeat, then add one roll. Farrow and Ball suggest one more roll than your estimate to allow for trimming and mistakes, and a spare from the same batch is also the only perfect match for a repair years later.