Wallpaper estimates go wrong when they divide wall area by roll area — that ignores the strips you trim off and the paper lost matching the pattern. This calculator uses the strip method installers use: strips per wall from the roll width, strip length rounded to the pattern repeat, and strips packed into rolls so offcuts from a tall wall can serve a short one. It handles US single and double rolls, European rolls, metric walls, and any number of walls.
Painting the other walls? The paint calculator gives gallons for the rest of the room. Replacing damaged drywall before papering? Use the drywall calculator, and the unit converter helps with labels in centimeters. Making curtains to match? The sewing fabric calculator rounds lengths to the pattern repeat the same way. For the full method with waste factors, see how much paint, wallpaper, and tile to buy.
Frequently asked questions
How many rolls of wallpaper do I need?
Count strips, not square feet. Divide each wall's width by the roll width and round up to get strips. Each strip is the wall height plus a few inches for trimming, rounded up to a whole pattern repeat (and on patterned paper, at least the height plus one full repeat). Divide the roll length by the strip length and round down to get strips per roll, then divide total strips by strips per roll and round up. For a 12×14 ft room with 8 ft walls and 20.5 in × 33 ft rolls, that is 34 strips at 3 per roll — 12 rolls.
What does pattern repeat mean?
The repeat is the vertical distance before the design starts over, printed on the label (often as V/R). Every strip has to start at the same point in the pattern so the motifs line up across the seams, which means you throw away part of the roll between strips. The usual rule of thumb is to allow the wall height plus one full repeat for every strip, and the calculator never counts less than that. A fresh roll also starts at an arbitrary point in the pattern, so it allows one repeat at the start of each roll. Random-match papers such as stripes and textures have no repeat waste.
What is the difference between straight match and drop match?
With a straight match, the pattern lines up horizontally at the same height on every strip, so each strip is cut identically. With a drop (half-drop) match, every other strip is shifted down half a repeat, so the design runs diagonally. Drop matches use more paper — on average an extra half repeat per strip — which the calculator adds to the aligned cut automatically; every strip is also floored at wall height plus one full repeat, so on some wall heights the two matches come out the same. The match type is shown on the label with a symbol or the words straight, drop, or random. If the label is unclear, the product page or sample book usually states it.
Should I subtract doors and windows?
Most professional paperhangers do not. The short pieces above a door and above and below a window still have to be cut from rolls, and pattern matching around openings wastes more than you might expect. The extra paper also covers a mistake and gives you matching spares for future repairs. If you do tick the deduction, the calculator only subtracts the full-height strips an opening actually replaces — a 3 ft door saves one 20.5 in strip, not 21 sq ft.
What is a double roll of wallpaper?
In the US, wallpaper is usually priced per single roll but sold as double rolls — one continuous piece twice as long, commonly 20.5 in × 33 ft. A double roll wastes less, because there is only one leftover end instead of two. European and UK rolls are a single 53 cm × 10.05 m piece. Enter the exact width and length printed on your label, and the calculator counts rolls of that size. When you pick a single-roll size, it also shows how many double rolls you would need.