Interior & Finishing · Calculator
Wallpaper Calculator
This wallpaper calculator counts how many rolls you need the way a paper hanger does: strip by strip, with the pattern repeat and the trim allowance built in. Enter your wall widths, roll size and repeat.
Your walls
Each door saves 1 full strip. Windows are not subtracted.
The most common American bolt, about 56 sq ft.
On the label. Use 0 for random or free match.
Pattern lines up straight across.
How to calculate wallpaper rolls
Square footage alone undercounts. You cannot use a 2 ft scrap to finish a full-height strip, so what matters is how many full-height strips each roll gives you. That depends on your wall height and the pattern repeat.
Start with the strip length. Add 4 inches to the wall height for trimming at the ceiling and baseboard. If the paper has a repeat, round up to a whole number of repeats so every strip starts at the same point in the design. We also hold back one repeat per roll for lining up the very first strip.
Then count strips. Divide the total width of all the walls by the roll width and round up. In a room, the narrow piece left after turning a corner gets hung on the next wall, so walls share strips. Divide by strips per roll and round up again.
Wallpaper roll sizes
Roll sizes vary by country and maker, so always read the label. The last column shows full strips per roll on an 8 ft wall, first with no repeat and then with a 21 in repeat.
| Roll | Width | Length | Area | Strips at 8 ft (none / 21 in repeat) |
|---|---|---|---|---|
| US double roll | 20.5 in | 33.0 ft | 56 sq ft | 3 / 3 |
| US single roll | 20.5 in | 16.5 ft | 28 sq ft | Sold as double bolts |
| Euro roll | 20.9 in | 33.0 ft | 57 sq ft | 3 / 3 |
| 27 in x 27 ft | 27.0 in | 27.0 ft | 61 sq ft | 3 / 2 |
Notice how a 33 ft roll gives only 3 full strips on an 8 ft wall once the trim allowance is added. The leftover piece, roughly 5 to 8 ft, is what you use above doors and below windows.
Pattern repeat and match types explained
The pattern repeat is the vertical distance before the design starts over. It is printed on the roll label, often with a symbol for the match type. Common repeats run from 0 (random) to about 25 inches.
A straight match lines up across every strip at the same height. A half-drop shifts every other strip down half a repeat, so you need more paper to land the pattern in the right spot. This calculator adds half a repeat to every strip for drop matches, the usual industry allowance.
Doors and windows: the calculator takes away one full strip for each standard 36 in door, because the short piece above the door comes from roll offcuts. It does not subtract windows, since the pieces above and below a window still need to match the pattern and use nearly a full strip between them.
| Match | How it hangs | Waste |
|---|---|---|
| Random / free | Any strip next to any other. Stripes, grasscloth, textures. | Lowest |
| Straight | Design lines up straight across at the same height. | Up to 1 repeat per strip |
| Half drop | Every other strip drops half a repeat. | About half a repeat more per strip |
| Reverse hang | Every other strip is hung upside down. Common on grasscloth. | Like random |
Tips before you order wallpaper
- Buy the same batch (lot) number. Every print run is slightly different in color. Check that all rolls share a lot number before you open any of them.
- Order an extra roll. Miscuts happen, and a matching roll is hard to find a year later when you need a repair.
- Strip and prep the walls first. New paper over old paper bubbles and peels. If steam and scoring will not lift the old layer, a heat gun on a low setting softens the paste: see our heat gun uses guide. A rigid scraper blade on an oscillating tool clears dried adhesive.
- Prime with a wallpaper primer. It seals the drywall so paper slides into place and comes off cleanly the next time.
- Papering only one wall? Enter just that wall here, and figure paint for the other three with the paint calculator.
Odd-shaped room?
Frequently asked questions
How many rolls of wallpaper do I need for a 12x12 room?
About 11 US double rolls for a 12x12 room with 8 foot walls and one door, including one spare. Each 33 foot roll gives 3 full-height strips once you add the trim allowance, and the room needs about 28 strips. The strip count matters more than the square footage.
How many square feet does a roll of wallpaper cover?
A US double roll (20.5 inches by 33 feet) is about 56 square feet, and a Euro roll is about 57 square feet. Usable coverage is lower, often 45 to 50 square feet, because you lose paper trimming each strip and matching the pattern.
What is a pattern repeat on wallpaper?
The pattern repeat is the vertical distance before the design starts over, printed on the label in inches or centimeters. Every strip has to start at the same point in the pattern, so a larger repeat wastes more paper per strip.
What is the difference between straight match and drop match?
With a straight match the design lines up straight across from one strip to the next. With a half-drop match every other strip is shifted down by half a repeat, which wastes more paper, so plan on about half a repeat extra per strip.
Should I buy an extra roll of wallpaper?
Yes. Buy at least one extra roll from the same batch or lot number. A roll bought later can come from a different print run with a visible color shift, and a spare covers miscuts and future repairs.
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