Wallpaper Calculator
Find how many rolls of wallpaper to buy using the strip method, which accounts for wall height and pattern repeat the way installers do.
Formulas shown on this page · Last reviewed October 2026
The strip method
Wallpaper is hung in vertical strips, so counting rolls by square footage is unreliable. This calculator works out how many strips the room needs and how many of them one roll can supply.
strip length (in) = wall height × 12 + pattern repeat
strips per roll = floor(roll length in ÷ strip length)
strips needed = ceil(wall length in ÷ roll width in) × (1 + waste)
rolls = ceil(strips needed ÷ strips per roll)
Strips per double roll (33 ft roll)
| Pattern repeat | 8 ft wall | 9 ft wall |
|---|---|---|
| None / random match | 4 | 3 |
| 12 in | 3 | 3 |
| 24 in | 3 | 3 |
| 36 in | 3 | 2 |
Prices for double rolls range from about $30 for basic vinyl to $150 or more for grasscloth and designer prints, so the pattern repeat can change the bill noticeably.
Practical tips
- Buy all rolls from the same batch number so the color matches, and keep a spare roll for repairs.
- Check whether the pattern is a straight match, half-drop or random – half-drop patterns need extra length.
- Wall height includes the few inches you trim at the ceiling and baseboard; the repeat figure covers the rest.
- For a single accent wall, enter that wall's length in "Wall perimeter" mode.
Frequently asked questions
How many rolls of wallpaper do I need for a 12×12 room with 8 ft walls?
The perimeter is 48 ft, or 576 inches. With 20.5 inch wide rolls you need ceil(576 ÷ 20.5) = 29 strips. A 33 ft double roll is 396 inches long, so a 96 inch strip (no pattern repeat) gives 4 strips per roll and you need 8 double rolls before waste. With a 12 inch repeat each strip is 108 inches, only 3 fit on a roll, and the total rises to 10 rolls.
How much wallpaper is in a double roll?
A standard US double roll is 20.5 inches wide and about 33 feet long, roughly 56 sq ft. A single roll is half of that, about 28 sq ft. After trimming and pattern matching, only about 40–45 sq ft per double roll is usable, which is why square footage alone underestimates the order.
What is a pattern repeat and how does it affect the order?
The pattern repeat is the vertical distance before the design repeats. Each strip must be cut longer by up to one repeat so patterns line up, so the strip length is wall height plus the repeat. A larger repeat means fewer strips per roll and more rolls overall – see the table above.
Do I subtract windows and doors?
You can subtract about 3 feet of width for each door or large opening, and the calculator does this. Windows are usually not deducted because you still need strips above and below them. Check roll size too: European rolls are often about 21 inches wide and 33 feet long, sold as single rolls covering around 57 sq ft.