Wallpaper Calculator

How to calculate how much wallpaper you need

Wallpaper is hung in vertical strips from ceiling to baseboard, so the number of rolls depends on how many full strips you can cut from one roll. This is the strip method that manufacturers describe, and it is the one this calculator uses. Manufacturers do not all round the strips the same way. Thibaut asks for the total width of all the walls as a single number, which is the same as rounding up once on the total. James Dunlop Textiles counts the drops of each wall separately and adds them, and any part-width counts as a full width. Counting wall by wall can add strips:

A part of a strip counts as a whole strip, because you cannot hang half a width without cutting a full one. The same goes for the roll: a leftover piece shorter than one strip cannot make another floor-to-ceiling strip. The pattern repeat goes in the strip length as a whole repeat, as James Dunlop Textiles does in its guide. If your paper has a random or free match, enter 0 as the repeat, because no matching is needed. By default the calculator rounds up the strips on the total width. Tick Round up each wall separately to count wall by wall as James Dunlop does. The result also shows the other count next to yours, so you can see the gap. The manufacturer you follow decides which one to use. Each measurement accepts feet and inches written as 8'6", and you can switch any box to inches, yards or meters.

Example: a 12 ft by 14 ft room with a 12 inch repeat

A room is 14 ft long and 12 ft wide with 8 ft walls. The wallpaper is a 20.5 inch by 33 foot roll with a 12 inch pattern repeat, and we allow 4 inches of trim per strip. This is what the calculator does with those numbers:

Round each wall on its own and the same room changes. The two 14 ft walls take 168 ÷ 20.5 = 8.20, so 9 strips each, and the two 12 ft walls take 144 ÷ 20.5 = 7.02, so 8 strips each. That is 2 × 9 + 2 × 8 = 34 strips instead of 31, and 34 ÷ 3 = 11.33, so 12 rolls instead of 11. The extra strips come from the parts of a width that the total-width count shares between walls.

Why the area method falls short

Many quick estimates multiply the wall area and divide by the area of a roll. For the same room that is 52 × 8 = 416 square feet of wall, a roll of 20.5 inches by 33 feet holds 56.38 square feet, and 416 ÷ 56.38 = 7.38, which rounds up to 8 rolls. The strip method gives 11. The area method is short by 3 rolls, and it falls short for three reasons:

• It assumes you use every inch of the roll. In the example each roll gives 3 strips of 112 inches and the last 60 inches are too short for another strip.
• It ignores the trim. Four inches on every strip add up over 31 strips.
• It ignores the pattern repeat. Matching the design from strip to strip needs extra length on every strip, and a bigger repeat can remove a whole strip from each roll.

The area method is only a sanity check. It is close when the paper has no pattern and the strips fit the roll almost exactly, and it is too low in most other cases. The calculator shows both numbers so you can see the gap.

How the pattern repeat changes the rolls

Same room, same roll, same 31 strips. Only the strip length changes, and with it the number of strips you get from each roll.

Notice the step from 3 strips per roll to 2. A 36 inch repeat makes every strip 136 inches long, a 396 inch roll holds only two of them, and the rolls jump from 11 to 16. Just 4 inches of trim is enough to turn 4 strips per roll into 3 in this room. That is why a small change in the repeat or the trim can add rolls.

Roll sizes from manufacturer listings

Roll sizes are not standard across brands, so use the width and length printed on your wallpaper. These are three listings we opened in October 2026. Choose them in the roll size box to fill in the numbers.

Sources: York Wallcoverings, Chesapeake Spinney, York Wallcoverings, Magnolia Home Garden Terrace and Brewster Home Fashions, Alice Mint Greenhouse. The paper per roll is width times length. York states about 60.8 square feet for the 27 inch roll and Brewster states about 57.5 square feet for its roll. Thibaut notes that its wallpapers are priced by the single roll and packaged in double rolls, so for those a double roll counts as two single rolls. European rolls are about 10 meters by 53 centimeters, which is 32.8 feet by 20.9 inches, according to a retailer (Selected Wallpapers), and that matches the Brewster listing. We could not find an open manufacturer listing with the length of a single roll, so the calculator does not offer one. Type your own length if your store sells single rolls.

Trim allowance, openings and waste

Trim. York’s installation guide says to measure the wall height and allow approximately 4 inches of additional length, roughly 2 inches at the ceiling and 2 at the baseboard, for trimming, and to account for the pattern repeat and match (York installation guide). The example above starts with 4 inches for that reason. You can change it, and an empty box means 0.

Doors and windows. Thibaut states that deducting doors or windows is not recommended, and James Dunlop Textiles recommends treating walls with doors and windows as full walls, because about as much paper is used cutting and piecing around the openings. That is why the openings box is optional. If you use it, each opening is turned into the width of full-height wall that has the same area (opening area divided by wall height) and that width comes off the distance around the room. This conversion is our own approximation, not a manufacturer rule.

Waste. Thibaut recommends ordering up to 20% additional to accommodate repeats, complex room designs and error. Type the figure you choose in the waste box, or leave it empty to see the result without it. The calculator applies the percentage to the strips before dividing by the strips per roll.

What this calculator does not do

It gives the strips, the strips per roll and the rolls, plus an area check for comparison. It does not give prices. It does not model the extra paper that a drop (half-drop) match needs, because we could not find an open manufacturer formula for it. If your paper is a drop match, add a waste percentage and confirm the quantity with the supplier. It does not handle sloped ceilings, arches, borders, murals printed to size or peel-and-stick panels. Wallpaper colors can vary between production runs, so order every roll from the same run number.

Frequently asked questions