Wallpaper Calculator
Enter room dimensions, openings, roll coverage, pattern repeat and waste. It accounts for matching repeats and gives rolls to buy (rounded up).
| Room perimeter | ft |
| Wall height | ft |
| Windows/doors area | sq ft |
| Roll width | in |
| Roll length | ft |
| Pattern repeat | in |
| Waste allowance | % |
Result
Your result will appear here.
How it works
Calculate wall area (perimeter × height minus openings), divide by usable area per roll accounting for pattern repeat, add waste allowance, round up to full rolls.
Formula
Wall area = (perimeter × height) − doors/windows
Area per roll = (roll width/12) × roll length
Rolls = ceil((wall area × (1 + waste%)) / area per roll)
Worked example
Perimeter 48 ft, height 8 ft = 384 sq ft, minus 40 sq ft openings = 344 sq ft. A 20.5"×33' roll gives ~56 sq ft; at 10% waste need ~378 sq ft → 7 rolls.
Assumptions
Pattern repeat adds waste. Corners, awkward angles and trimming increase usage. Buy from the same batch.
Reading the result
Always round up - you can't buy partial rolls. Keep extra for future repairs.
For general information only. Actual rolls depend on pattern match and installation.
How to use the Wallpaper Calculator
It takes a few seconds, and every figure is calculated in your browser.
- Enter the room perimeter.
- Enter the wall height.
- Enter the windows/doors area.
- Enter the roll width.
- Enter the roll length.
- Enter the pattern repeat.
- Press Calculate — the result appears in the dark panel beside the form.
- Use Copy, CSV, Share or Print under the result if you want to keep it.
Wallpaper Calculator — frequently asked questions
What formula does the Wallpaper Calculator use?
Wall area = (perimeter × height) − doors/windows Area per roll = (roll width/12) × roll length Rolls = ceil((wall area × (1 + waste%)) / area per roll)
How does the Wallpaper Calculator work?
Calculate wall area (perimeter × height minus openings), divide by usable area per roll accounting for pattern repeat, add waste allowance, round up to full rolls.
What assumptions and limitations should I know about?
Pattern repeat adds waste. Corners, awkward angles and trimming increase usage. Buy from the same batch.
Can you walk through a worked example?
Perimeter 48 ft, height 8 ft = 384 sq ft, minus 40 sq ft openings = 344 sq ft. A 20.5"×33' roll gives ~56 sq ft; at 10% waste need ~378 sq ft → 7 rolls.
Last updated 10 November 2026 · Formula, worked example and assumptions are documented above, and every result is calculated in your browser.