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Wallpaper Calculator
Buying wallpaper is easy to get wrong: order too little and the last wall is left bare while the store is out of your batch; order too much and you have paid for rolls you will never unroll. Enter your total wall area and the area taken up by doors and windows, and this free wallpaper calculator tells you how many standard rolls to buy, with 10% extra for matching the pattern.
A standard door is about 21 sq ft (3 ft × 7 ft) and a typical window about 15 sq ft. Add them up and enter the total.
| Net wall area | 260 sq ft |
| Area with waste | 286 sq ft |
| Rolls needed | 6 |
| Area the rolls cover | 336 sq ft |
Results are estimates for planning only. Check the coverage printed on the rolls you buy — roll sizes vary.
Common wallpaper jobs
| Net wall area | With 10% waste | Rolls (56 sq ft each) |
|---|---|---|
| 100 sq ft | 110 sq ft | 2 rolls |
| 200 sq ft | 220 sq ft | 4 rolls |
| 260 sq ft | 286 sq ft | 6 rolls |
| 400 sq ft | 440 sq ft | 8 rolls |
| 600 sq ft | 660 sq ft | 12 rolls |
How it works
Wallpaper is bought by the roll, and a standard roll covers about 56 square feet. That number is not a law of nature — it is the usable area of a typical roll after the strips are cut to the height of your walls — so the first thing to check is the coverage printed on the roll you plan to buy. If your roll covers 60 square feet instead of 56, change the coverage figure in the calculator and the answer will adjust. Everything else in the calculation follows three simple steps: measure the walls, subtract the openings, and add waste for the pattern.
Measuring the walls is the same as measuring for paint or drywall. For each wall, multiply its length by its height, then add all the walls together. A room with two 12-foot walls and two 10-foot walls, all 8 feet high, has (12 × 8) + (12 × 8) + (10 × 8) + (10 × 8) = 352 square feet of wall. If the ceiling is sloped, measure the wall in sections — a rectangle for the straight part and a triangle for the sloped part — and add them together. Measure twice; a wall you forgot is the most common reason a wallpaper job runs short.
Doors and windows come out next, because no wallpaper goes on them. A standard interior door is about 3 feet wide by 7 feet tall, which is 21 square feet. A typical window is around 15 square feet, though large windows can be 20 or more. Measure each opening (width × height) and add them up. In the example on this page, 300 square feet of wall minus 40 square feet of openings leaves 260 square feet of net wall to cover.
The waste allowance is what makes wallpaper different from paint. With a patterned paper, each strip has to line up with the one beside it so the design flows across the wall without a visible jump. That means the top of every strip is cut to match the pattern, and the piece cut off the top — and sometimes the bottom — is thrown away. On a tall wall with a large repeating pattern, that waste can be a foot or more per strip. Ten percent is the standard allowance for a normal repeating pattern. For a large pattern with a long repeat, choose 15%. For plain paper, or a small random pattern that needs no matching, you can use 0% — though keeping one spare roll is still wise in case a strip is damaged while hanging.
Two buying tips matter more than the arithmetic. First, buy all your rolls at once, and check that they are from the same batch number. Wallpaper from different batches can differ very slightly in colour, and the difference only shows up once it is on the wall in daylight. Second, round up, always. The calculator rounds up to whole rolls because part of a roll cannot be bought, and the spare paper from the last roll is exactly what you want in the cupboard for the day a chair scuffs a strip or a corner peels.
Worked example
Emma is wallpapering her living room. She measures the walls and gets 300 square feet in total. The room has one door (21 square feet) and one large window (about 19 square feet), so the openings add up to 40 square feet. She has chosen a paper with a repeating floral pattern, so she uses the standard 10% waste allowance.
Step 1: Subtract the openings: 300 − 40 = 260 square feet of net wall.
Step 2: Add 10% for pattern matching: 260 × 1.10 = 286 square feet.
Step 3: Divide by one roll: 286 ÷ 56 = 5.11 rolls.
Step 4: Round up to whole rolls: 6 rolls.
Emma buys 6 rolls. They cover 336 square feet in total, which is 50 square feet more than the 286 she needs — that spare paper is the pattern-matching waste and her safety margin for the one strip that never goes up straight the first time.
FAQ
How many rolls of wallpaper do I need for 300 square feet of wall?
It depends on the doors and windows. With 40 square feet of openings, the net area is 260 square feet. Adding 10% for pattern matching gives 286 square feet, and at 56 square feet per roll that is 6 rolls.
How much area does one roll of wallpaper cover?
One standard roll covers about 56 square feet. This calculator uses 56 square feet per roll, but always check the coverage printed on the roll you buy, since sizes vary.
Why add 10% waste when buying wallpaper?
Wallpaper with a pattern has to line up from one strip to the next, so some paper is cut away at the top and bottom of every strip to match the design. The 10% allowance covers that matching waste and small cutting mistakes.
Should I subtract doors and windows from the wall area?
Yes. Measure the total wall area, then subtract the area of doors and windows, because no wallpaper goes on those openings. Enter both figures in the calculator and it does the subtraction for you.
What if my wallpaper has no pattern to match?
Plain wallpaper and small random patterns need less extra paper, because strips can be cut with almost no waste. You can still keep a small allowance for mistakes, but the full 10% is mainly for large repeating patterns.