Wallpaper Calculator: How Many Rolls Do You Need?
Buying too few rolls means a mid-project trip back to the store — and the new batch may be a different dye lot. Buying too many wastes money. This calculator gives you an exact roll count for any room, any roll size, and any pattern repeat, with a built-in waste buffer so you buy right the first time.
To calculate wallpaper rolls needed, divide your net wall area (perimeter × height, minus doors and windows) by the usable coverage per roll, then add 10% for waste. A standard US double roll covers roughly 25–30 sq ft net. For a typical 12×12 ft room with 8 ft ceilings, one door, and two windows, you need approximately 9–11 double rolls.
Wallpaper Calculator
Enter your room & roll details — get an instant roll count
ft
ft
ft
doors
Each door ~20 sq ft
windows
Each window ~15 sq ft
ft
US double roll ~27 ft; EU ~33 ft
in
US ~27 in; EU ~20.5 in
in
Enter 0 for no pattern / straight match
%
10% standard; 15–20% large repeats
How to use this calculator
- Choose a mode. Use “Room dimensions” if you have a tape measure handy. Use “I know my wall area” if you already calculated net square footage.
- Enter room size. Type the length, width, and ceiling height in feet. Count your doors and windows — the calculator deducts 20 sq ft per door and 15 sq ft per window automatically.
- Enter roll specs. Check the wallpaper label for roll length (ft) and roll width (inches). US double rolls are typically 27 in × 27 ft. European single rolls are typically 20.5 in × 33 ft.
- Enter pattern repeat. Look for “pattern repeat” on the label. Enter 0 for a straight match or no pattern.
- Set waste allowance. Leave at 10% for plain or straight-match paper. Use 15–20% for large repeats or complex rooms.
- Click Calculate. The result shows total rolls needed, usable area per roll, and a numbered step-by-step breakdown you can screenshot before going to the store.
What is a wallpaper roll, and why does roll size matter?
A wallpaper roll is a pre-cut length of printed or textured paper sold in a fixed width and length. Roll size determines how many strips you can cut from one roll, which directly controls how many rolls you need to buy. A roll that is 6 inches wider than another can yield one extra strip per roll, cutting your total roll count by 10–15% in a typical room.
In the US, the industry standard is the double roll: 27 inches wide and 27 feet long (~60 sq ft gross). Stores price wallpaper per single roll but ship in double rolls, so you always buy in pairs. European rolls are narrower (20.5 in) and slightly longer (33 ft), giving ~56 sq ft gross per single roll.
| Spec | US double roll | EU single roll |
|---|---|---|
| Width | 27 inches | 20.5 inches |
| Length | 27 feet | 33 feet |
| Gross area | ~60.75 sq ft | ~56.4 sq ft |
| Net usable area (10% waste) | ~54.7 sq ft | ~50.8 sq ft |
| Typical strips (8 ft ceiling) | 3 strips | 4 strips |
| Sold as | Double roll (2 singles) | Single roll |
The wallpaper formula explained
Rolls needed = ceil( (Net Wall Area / Usable Area per Roll) × (1 + Waste%) )Where:
Net Wall Area = (Perimeter × Height) − (Doors × 20) − (Windows × 15) [sq ft]
Strips per Roll = floor( Roll Length / Effective Strip Length )
EffectiveSources & References
Written and fact-checked by Dr Irfan Mansuri. External links open in a new tab and are provided for further reading and verification.