Wallpaper Calculator with Pattern Repeat

Count rolls in strips rather than square feet, so the pattern repeat is allowed for.

Your room

The wall

For a feature wall this is just that wall. For a whole room, run each wall on its own and add the strips together, because every internal corner ends a strip and starts a new one: a single perimeter figure comes out two to four strips short on an ordinary room. Measure along the floor rather than the ceiling, since the two are rarely the same.
Measure the tallest wall in the room. Old houses settle, and cutting every strip to the shortest wall is how you run out of paper at the far corner.
Two inches at each end is normal, and it is what lets you slide a strip up or down to match the pattern before trimming at the ceiling and the skirting.

The paper

Printed on the roll label. American residential paper is usually 20.5 or 21 inches, and commercial goods run 27 or 36. The width sets how many strips you need, so it matters more than the length.
American paper is usually sold as a double roll, or bolt: 33 feet at 20.5 inches wide, 27 feet at 27 inches, 24 feet at 36. Enter the length of the unit you are actually buying.
The vertical distance before the design starts again, printed on the label. Textures, grasscloths and plain stripes are a random match, so they take a zero here and waste almost nothing.
A straight match repeats at the same height on every strip. A half drop steps the design down by half a repeat on alternate strips, which is why it wastes more. A random match does not line up at all and can be cut anywhere.
Price
Price the same unit you gave a length for. Paper quoted per single roll but sold in double rolls is the most common way to be out by a factor of two.
Rolls to buy
8 rolls
29%
is waste
Strips to hang 24 strips
Strips from one roll 3 strips
Cut each strip at 105 in
Wall area
320 sq ft
Paper bought
451 sq ft

What the repeat costs

Lost to the repeat, per strip 5 in
Bought but not hung 29%
Does the paper fit the wall Every strip comes off the roll in one piece

What it costs

Material cost $440
Cost per square foot of wall $1.38

Every figure here is a planning estimate, not a professional takeoff. Yields, waste factors and code requirements vary by product, supplier and jurisdiction, so confirm quantities against the manufacturer’s data and your local building department before you order.

Generated by Mathterial

Wallpaper is not sold by the square foot and it is not hung by the square foot either. It comes off a roll in full width strips, so the question is how many whole strips a roll gives you, and that is decided by the pattern repeat rather than by the area of the wall. This is a wallpaper calculator with repeat built in, so it works in strips, which is how the job is actually done.

Why area is the wrong unit

Divide the wall by the coverage printed on the label and you get a number that is right only for a plain paper. The moment there is a pattern, every strip has to start at the same point in the design as the strip beside it, so a strip is not cut to the height of the wall. It is cut to the next whole repeat above it, and the offcut goes in the bin.

What a strip actually costs you

cut length = wall height + trim, rounded up to a whole repeat

A 100 in drop on a 24 in repeat is cut at 120 in, so 20 in of every strip is waste

Then it happens again at the roll. A 33 foot roll is 396 inches, and at a 120 inch cut you get three strips with 36 inches left over, too short for a fourth. The paper you buy is decided by those two roundings, not by the arithmetic of area.

Where the repeat actually bites

Here is the part most calculators hide: the repeat often changes nothing at all, and then suddenly changes everything. On an 8 foot wall the cut goes from 100 inches plain to 120 inches on a 24 inch repeat, and both give three strips from a 33 foot roll. On a 10 foot wall the same change takes the cut from 124 to 144 inches, which drops the roll from three strips to two, and the order goes up by half.

The calculator shows the strips per roll for exactly that reason. If you are one inch of cut away from losing a strip per roll, that is worth knowing before you order, because the fix is sometimes a different paper rather than more of this one.

Straight match and half drop

  • Random match. Textures, grasscloths, plain stripes. Nothing to line up, so a strip is cut to the wall and the waste is only the trim.
  • Straight match. The design repeats at the same height on every strip, so each cut rounds up to a whole repeat.
  • Half drop. Alternate strips step down by half a repeat, so the design runs diagonally across the wall. It takes three strips to get back to where the pattern started, and the extra half repeat usually pushes the cut length up a notch. Not always, though: if the straight cut already had room to spare, the offset can land inside the same repeat and cost nothing. Run both and see.

A word on the waste figure

The page reports what you bought against what goes on the wall, and that number looks alarming on a plain rectangular room: nearly a third on some combinations. Two things are true about it. The offcuts are not all wasted, because the short pieces go over doors and above windows, and paper is sold in whole rolls whatever you do, so some of that number is simply the shape of the product.

What the figure is good for is comparing papers. Run the same room with a 12 inch repeat and a 24 inch repeat and the difference between them is real money, decided before anybody picks up a brush.

Wallpaper calculator FAQ

How much wallpaper do I need?

Work it out in strips rather than square feet. Divide the wall run by the roll width for the number of strips, round the cut length up to a whole pattern repeat, see how many of those cuts fit a roll, then divide.

How does the pattern repeat change how much I need?

It rounds every strip up. A 100 inch drop on a 24 inch repeat is cut at 120 inches, and if that pushes the strips per roll from three down to two, the order goes up by half.

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

A straight match repeats at the same height on every strip. A half drop steps alternate strips down by half a repeat, so the design runs diagonally, and it uses more paper than a straight match with the same repeat.

How big is a roll of wallpaper?

American paper is usually sold as a double roll, or bolt: 33 feet at 20.5 or 21 inches wide, 27 feet at 27 inches, 24 feet at 36. Enter the unit you are actually buying, because paper priced per single roll and sold in doubles is the classic mistake.