Wallpaper Calculator
Calculate how many rolls of wallpaper you need for any room.
Enter dimensions, roll width, and pattern repeat to get an accurate roll count with waste.
Wallpaper quantity calculation requires measuring the total wall area, accounting for doors and windows (which don’t need coverage), adjusting for pattern repeat waste, and converting to the number of rolls needed.
Step 1 — Net wall area:
Total Wall Area = Perimeter × Wall Height
Perimeter = 2 × (Room Length + Room Width)
Net Area = Total Wall Area − (Door Area × Number of Doors) − (Window Area × Number of Windows)
Standard door: 7 ft × 3 ft = 21 ft². Standard window: 4 ft × 3 ft = 12 ft².
Step 2 — Usable area per roll:
Standard US wallpaper roll: 27 inches wide × 15 feet long = 28 sq ft Standard European roll: 20.5 inches wide × 33 feet long = 56 sq ft (double roll)
Usable Area per Roll = Roll Width × Roll Length × 0.85 (15% trim waste)
Step 3 — Pattern repeat adjustment: Each strip dropped to match the pattern wastes approximately one repeat per strip.
Strips per Roll = Roll Length ÷ (Wall Height + Pattern Repeat)
Actual Coverage = Strips per Roll × Usable Strip Width
Worked example: Room: 12 ft × 14 ft, 9 ft walls, 2 doors, 2 windows. US rolls (27" × 15 ft), 9-inch pattern repeat.
- Perimeter: 2 × (12 + 14) = 52 ft
- Total wall area: 52 × 9 = 468 sq ft
- Deductions: (2 × 21) + (2 × 12) = 42 + 24 = 66 sq ft
- Net area: 468 − 66 = 402 sq ft
- Strips per roll: 15 ÷ (9 + 0.75) = 1.54 → 1 strip per roll (conservative)
- Strip width: 27 inches = 2.25 ft
- Coverage per roll: 1 strip × 2.25 ft × 9 ft = 20.25 sq ft
- Rolls needed: 402 ÷ 20.25 = 19.9 → order 22 rolls (always add 10–15% overage)