CalculateY
Quick Answer
A room with four 12-foot walls and 8-foot ceilings (384 sq ft), minus 1 door and 2 windows, requires approximately 7 standard rolls (20.5 in x 33 ft) with no pattern repeat.
Enter the width of each wall, separated by commas
Common Examples
| Input | Result |
|---|---|
| 8 ft ceilings, walls 12, 12, 12, 12, roll 20.5 in x 33 ft, no repeat, 1 door, 2 windows | 333 sq ft net area, 7 rolls |
| 8 ft ceilings, walls 14, 14, 10, 10, roll 20.5 in x 33 ft, no repeat, 2 doors, 3 windows | 297 sq ft net area, 6 rolls |
| 9 ft ceilings, walls 15, 15, 12, 12, roll 27 in x 27 ft, 12 in repeat, 1 door, 2 windows | 435 sq ft net area, 9 rolls |
| 8 ft ceilings, walls 10, 10, 10, 10, roll 20.5 in x 33 ft, 21 in repeat, 1 door, 1 window | 284 sq ft net area, 7 rolls |
How It Works
The Formula
Net Wall Area = Total Wall Area - Door Area - Window Area
Usable Coverage per Roll = Strips per Roll x Roll Width (ft) x Wall Height
Rolls Needed = ceil(Net Wall Area / Usable Coverage per Roll)
Where:
- Total Wall Area = Wall Height x sum of all wall widths
- Door Area = Number of Doors x 21 sq ft (standard door opening)
- Window Area = Number of Windows x 15 sq ft (standard window opening)
- Strips per Roll = floor(Roll Length in inches / Strip Height in inches)
- Strip Height = Wall Height in inches, adjusted upward to the nearest pattern repeat if applicable
Pattern Repeat
Many wallpapers have a pattern that must align from strip to strip. The pattern repeat is the vertical distance before the design repeats. Each strip must start at the same point in the pattern, which means extra wallpaper is trimmed from each strip. For example, with 96-inch (8-foot) walls and a 21-inch repeat, each strip must be cut at 105 inches (the next multiple of 21 above 96), wasting 9 inches per strip. This significantly increases the number of rolls needed.
Standard Roll Sizes
American single rolls are typically 20.5 inches wide and 33 feet long (about 56 sq ft). Euro rolls are commonly 20.5 inches wide and 33 feet long as well, though some are 21 inches by 33 feet. Wider rolls (27 inches or 28 inches) and different lengths (27 feet) also exist. Double rolls are twice the length of a single roll.
Trimming and Waste
Beyond pattern repeat waste, additional material is lost to trimming at the top and bottom of each strip (typically 2 to 4 inches). Ordering one or two extra rolls beyond the calculated amount provides a buffer for mistakes and future repairs.
Worked Example
For a room with 8-foot ceilings and four walls measuring 12, 12, 14, and 14 feet, with a standard 20.5 in x 33 ft roll, no pattern repeat, 2 doors, and 3 windows: Total wall area = 8 x (12 + 12 + 14 + 14) = 416 sq ft. Deductions = (2 x 21) + (3 x 15) = 87 sq ft. Net area = 329 sq ft. Strip height = 96 inches (8 ft). Strips per roll = floor(396 / 96) = 4 strips. Usable per roll = 4 x (20.5 / 12) x 8 = 4 x 1.708 x 8 = 54.67 sq ft. Rolls needed = ceil(329 / 54.67) = 7 rolls.