Wallpaper Calculator
Estimate wallpaper rolls, wall area, strips, pattern repeat allowance, waste allowance, and optional material cost for room wallpaper projects.
Results
Wallpaper estimates are approximate. Real roll needs can vary by pattern matching, half-drop designs, wall layout, trimming, damaged strips, alcoves, windows, doors, and whether rolls are sold as single, double, or European-size rolls.
Use this Wallpaper Calculator to estimate the number of wallpaper rolls and strips needed for a room. Enter the room dimensions, opening area, roll size, pattern repeat, and waste allowance.
Wallpaper Calculation Method
Room perimeter = 2 × (room length + room width)
Gross wall area = room perimeter × wall height
Net wall area = gross wall area − door and window area
For patterned wallpaper, the strip length is rounded up to the next complete pattern repeat:
Adjusted strip length = pattern repeat × ceiling(wall height ÷ pattern repeat)
Strips per roll = floor(roll length ÷ adjusted strip length)
Strips needed = ceiling(net wall area ÷ strip coverage area)
Rolls needed = ceiling((strips needed ÷ strips per roll) × (1 + waste percentage ÷ 100))
Example
Suppose a room is 12 ft long, 10 ft wide, and 8 ft high. Openings cover 40 ft². The wallpaper roll is 20.5 inches wide and 33 ft long, with a 20-inch pattern repeat and 10% waste.
Room perimeter = 2 × (12 + 10) = 44 ft
Gross wall area = 44 × 8 = 352 ft²
Net wall area = 352 − 40 = 312 ft²
The 8-ft wall height is rounded up to five complete 20-inch pattern repeats, giving an adjusted strip length of approximately 8.33 ft.
Approximately three complete strips can be cut from each 33-ft roll. After allowing for the required strips and 10% waste, the project needs approximately 9 rolls.
Important Notes
- Use the exact roll width, roll length, pattern repeat, and match type shown on the wallpaper label.
- Large repeats, half-drop patterns, trimming, damaged strips, corners, and irregular walls may increase the quantity required.
- Avoid deducting small openings too aggressively because full strips may still be needed around doors and windows.
- Round the result up to a whole roll and order rolls from the same batch or dye lot when possible.
- The calculator does not estimate adhesive, lining paper, wall preparation, installation tools, delivery, or labour.