How many rolls of wallpaper?

Half the roll is not on your wall

A standard double roll holds around 56 square feet of paper. You will get nowhere near that onto the wall. Between trimming the top and bottom of each drop and matching the pattern between drops, the usable figure is closer to 28 square feet — which is the number this calculator works from, and the reason a room that looks like it needs six rolls actually takes eleven.

How much you lose depends on the pattern repeat. A plain or random-match paper wastes very little, and you can push the usable figure up towards 35 ft². A large repeat — anything over about 20 inches — means cutting each drop to align with the last, and the offcuts pile up fast. For those, drop the usable figure to 25 ft² or lower.

Doors and windows are subtracted here at 21 and 15 square feet, the same standard figures the paint calculator uses. Be a little careful with that: you cannot always use the paper saved above a door, because the drop still has to run full height to match the pattern on either side. On a heavily patterned paper, ignore the deductions entirely and paper the full perimeter.

Buy every roll in one go and check the batch number printed on the label. Wallpaper is printed in runs, and the colour shifts between them enough to see on a wall. This is the same trap as tile dye lots, and it ends the same way: a strip that does not match, and no way to buy more of the original.

A worked example: a 12 × 10 bedroom

A 12 × 10 foot bedroom with 8-foot ceilings has a perimeter of 44 feet and 352 ft² of wall. Take off a door and two windows and you have 301 ft² to cover. At 28 usable square feet per roll that is 10.8, so the calculator says 11 rolls. If the paper has a large pattern repeat and you drop the usable figure to 25 ft², the same room needs 13.

Papering a single accent wall is a much smaller order. The 12-foot wall behind the bed is 12 × 8 = 96 ft², which is 4 rolls at 28 ft² usable. Accent walls are also where the batch number matters most, because there is no break to hide a color shift.

Rolls for common rooms

8-foot ceilings, one door and one window, 28 ft² usable per roll.

Mistakes that cost money

• Hanging over unprepared walls. Fresh drywall needs a wallpaper primer, sometimes called sizing, or the paper bonds to the paper face of the drywall and tears it off when you remove it years later.
• Starting in a corner without a plumb line. Corners are rarely straight. Snap a plumb line one roll width from the corner and hang the first drop to it, or every drop after it will lean.
• Cutting all the drops before checking the match. Cut two drops, hang them, and confirm the pattern lines up before cutting the rest. A mistake on drop one repeats on every drop.
• Not ordering a spare roll. One extra roll from the same batch covers mistakes now and repairs later. Unopened rolls can often be returned.

What it costs

Wallpaper prices range widely: budget papers can cost $30 to $60 per roll in the US, while designer papers run well over $100. For the bedroom above, 11 rolls would cost roughly $330 to $660 at the budget end, plus paste (if the paper is not pre-pasted), primer and a smoothing tool. Check whether the price is per single or double roll, since retailers quote both.