Wallpaper Calculator
Use this wallpaper calculator to work out how many rolls a room needs from its wall sizes, door and window openings, roll size and pattern repeat. It counts strips, the way wallpaper is actually hung: the drop length of each strip, how many strips one roll gives and how many rolls to order. For paint on the same walls use the paint calculator, for wallboard use the drywall calculator and for floor or wall area use the square footage calculator.
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Rolls to buy (with waste)
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Strips needed
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Strips per roll
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Strip length (drop)
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Rolls before waste
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Wall area to cover
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Area of one roll
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Estimated cost
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Strips needed = wall width ÷ roll width, rounded up, where wall width is the wall area left after openings ÷ wall height. Strip length = wall height + trim allowance (4 in is the usual 2 in at the top and 2 in at the bottom), rounded up to a whole pattern repeat. Strips per roll = roll length ÷ strip length, rounded down. Rolls = strips ÷ strips per roll, plus the waste allowance, rounded up. Typical roll sizes: US double roll about 20.5 in × 33 ft, US single roll about 20.5 in × 16.5 ft, European roll 53 cm × 10.05 m; always check the label of your paper. Small openings may not save a whole strip, so set them to 0 if unsure. This is an estimate: confirm with your supplier.
Paint Calculator · Drywall Calculator · Square Footage Calculator · Tile Calculator
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How it works
- How many rolls of wallpaper do I need?
- Divide the room perimeter by the roll width to get the number of strips, work out how many full-height strips one roll gives, then divide and round up. A 12 × 14 ft room (52 ft around) with 8 ft walls, one door and two windows needs 27 strips of 20.5 in paper. A 33 ft double roll gives 3 strips of about 100 in, so that is 9 double rolls before waste.
- How does the pattern repeat change the amount?
- Each strip is cut to a whole number of repeats so neighbouring strips match. With 10 ft walls a plain strip is 124 in and a 33 ft roll gives 3 strips; with a 24 in repeat the strip becomes 144 in and the roll gives only 2. Enter the full repeat printed on the label, and 0 for plain or random-match paper.
- What is the difference between a single and a double roll?
- A double roll is twice as long as a single roll. Many US papers are sold as 20.5 in wide double rolls about 33 ft long (a single roll is about 16.5 ft), while many European papers are 53 cm wide and 10.05 m long. Prices are often quoted per single roll, so check which one the label and the price refer to.
- Should I subtract doors and windows?
- You can: this calculator removes their area from the wall area, which lowers the strip count a little. Because strips run from floor to ceiling, small openings often do not save a whole strip, and with a large repeat the pieces above and below a window rarely match, so set openings to 0 when in doubt.
- How much extra wallpaper should I buy?
- Many guides suggest adding about 10–15% for trimming, matching and mistakes; the Waste % field starts at 10% and you can change it. Buy every roll at once from the same batch or run number, because a later batch can differ in colour, and keep a spare roll for repairs.