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About This Calculator
Wallpaper is sold in rolls of standard dimensions, but calculating how many rolls you need requires accounting for pattern repeat, wall dimensions, and cutouts for doors and windows. Pattern matching can waste up to 25% of each roll depending on the repeat length. This calculator factors in all these variables to ensure you purchase enough rolls without excessive leftover waste.
Quick Tips
- 1 A standard US wallpaper roll covers about 28 usable square feet after waste.
- 2 Add one extra roll per room for pattern matching and future repairs.
- 3 Divide wall area by usable roll coverage and round up to whole rolls.
Example Calculation
Wall 14ft wide x 9ft tall, rolls 20.5" wide x 33ft long.
Wall area: 126 sq ft | Usable per roll: 45.5 sq ft | Rolls needed: 3 | Strips: 9
How to Calculate Wallpaper Rolls
Calculate the room perimeter (2 x length + 2 x width). Determine how many strips each roll yields by dividing the roll length by the room height. Calculate the total strips needed by dividing the perimeter (in inches) by the roll width. Subtract strips for doors and windows. Divide total strips by strips per roll and round up. Add 10% for waste, pattern matching, and mistakes.
Wallpaper Roll Sizes and Pattern Repeats
Standard US wallpaper rolls are 20.5 inches wide and 33 feet long (about 56 sq ft). European rolls are typically 21 inches wide and 33 feet long. Double rolls provide twice the length. Pattern repeats increase waste — a large pattern repeat (24 inches or more) may require 15-20% extra material beyond the basic calculation.
Frequently Asked Questions
A 12x15 foot room with 8-foot ceilings has 54 feet of perimeter. Using standard 20.5-inch rolls, you need approximately 8-10 single rolls after subtracting for doors and windows and adding 10% waste. This calculator provides the exact number.
A single roll is typically 33 feet long and a double roll is 66 feet long. Most wallpaper is sold in double rolls but priced per single roll. Always check whether the listing price is per single or double roll.
Buy 10-15% more than calculated. Pattern matching creates waste, and having extra ensures you can cover mistakes or repair damage later. Dye lots vary between production runs, so having enough from one batch is important.
Yes, subtract the area of doors and windows from the total wall area. Standard doors are about 21 sq ft and standard windows about 15 sq ft. However, be conservative with deductions — you still need partial strips around openings.