Wallpaper Calculator
Calculate rolls of wallpaper for a room from wall dimensions, doors and windows, roll size and pattern repeat.
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How to Calculate
Net wall area is the room perimeter × wall height, minus about 21 ft² per door and 15 ft² per window. Divide by the area of one strip (roll width × wall height) and round up to get the number of strips.
Each strip is cut to wall height plus 4 in for trimming top and bottom, plus one pattern repeat so the next strip can be lined up with the pattern. The number of whole strips you get from a roll sets the roll count; leftover pieces go above doors and windows.
In the US, a 20.5 in × 33 ft roll is often sold as a "double roll" (two single rolls of 16.5 ft packaged together). Enter the length of the roll you are actually buying and the result is in those rolls.
See our methodology for how every calculator on this site is built.
Worked Example: A Bedroom With a Patterned Paper
A bedroom 14 ft by 12 ft with 8 ft walls, one door and two windows. The paper comes in 20.5 in × 33 ft rolls with a 21 in pattern repeat.
- Perimeter: 2 × (14 + 12) = 52 ft
- Gross wall area: 52 × 8 = 416 ft²
- Openings: 21 (door) + 2 × 15 (windows) = 51 ft²
- Net wall area: 416 − 51 = 365 ft²
- One strip covers: (20.5 ÷ 12) × 8 = 13.67 ft²
- Strips: 365 ÷ 13.67 = 26.7, so 27 strips
- Length per drop: 96 in wall + 4 in trim + 21 in repeat = 121 in
- Drops per roll: 396 in ÷ 121 = 3.27, so 3 full drops
- Rolls: 27 ÷ 3 = 9 rolls
With no pattern repeat each drop is only 100 in, but 396 ÷ 100 is still 3.96, so you still only get three. The short leftovers from each roll are what you use above the door and under the windows. Buy a tenth roll from the same lot to cover a mistake.
How Pattern Repeat Changes the Count
Same 8 ft wall, 20.5 in × 33 ft roll:
| Pattern repeat | Length per drop | Drops per roll | Waste per roll |
|---|---|---|---|
| 0 in (random match) | 100 in | 3 | 96 in |
| 12 in | 112 in | 3 | 60 in |
| 21 in | 121 in | 3 | 33 in |
| 25 in | 125 in | 3 | 21 in |
| 27 in | 127 in | 3 | 15 in |
With 8 ft walls, the 33 ft roll is forgiving. At 9 ft walls, a drop with a 21 in repeat is 133 in and you only get two drops per roll. That is where a room suddenly needs half again as much paper.
Mistakes That Leave You Short
Single vs double rolls
US wallpaper is priced by the single roll but almost always sold in double-roll bolts. A listing that says "$45 per single roll, sold in double rolls" means $90 for what you take home. Enter the length on the bolt you are buying.
Different dye lots
Rolls printed in different runs can be visibly different in color. Check the lot number on every roll before you hang any of it.
Not planning the last seam
The pattern will not line up where the first and last strips meet. Start and finish in the least visible corner, usually behind the door.
Practical Tips
- Prime walls with a wallpaper primer. It makes hanging easier and removal far easier.
- Snap a plumb line for the first strip on every wall. Corners are not plumb.
- Cut all drops for a wall before hanging so you can match the pattern on the table.
- Book-fold pre-pasted paper for the time on the label so it relaxes before it goes up.
Rough Cost
Basic prepasted wallpaper starts around $25 to $60 per double roll, designer papers $100 to $300 and up. Professional hanging typically runs $2 to $6 per square foot of wall, or roughly $50 to $100 per roll.
Sources
Common questions
Frequently Asked Questions
How many rolls of wallpaper for a 12 × 12 room?
With 8 ft walls, one door and two windows, about 9 rolls of 20.5 in × 33 ft for a paper with no repeat, since each roll gives three full 8 ft drops. A large repeat can push it to 12 or 13.
What is a pattern repeat?
The vertical distance before the design starts over. Bigger repeats waste more paper, because each strip has to start at the same point in the pattern.
What is the difference between a single and double roll?
A US single roll is about 27 to 28 ft² of paper; a double roll is the same width and twice as long, sold as one piece so you get fewer short ends.
Should I buy extra wallpaper?
Buy at least one extra roll from the same batch (dye lot). A later order may not match the color exactly.
Do I subtract doors and windows?
Yes for standard doors and windows, which this calculator does. Small openings like outlets and vents are not worth subtracting.