How the roll count works
Wallpaper is hung in vertical strips, so the most accurate way to estimate it is by counting strips rather than square feet. First find how many strips go around the room, then how many usable strips each roll gives you.
Strip length = wall height + pattern repeat + 4 in trim
Strips per roll = roll length ÷ strip length, rounded down
Strips needed = (wall length − doors − ½ windows) ÷ roll width, rounded up
Rolls = strips needed ÷ strips per roll, rounded up
Example: a 12 × 12 ft room has 48 ft of wall at 8 ft high. Subtracting one 3 ft door and half of one 3 ft window leaves 43.5 ft, which is 26 strips of 20.5 inch paper. With no repeat, each strip is 100 inches, so a 33 ft roll gives 3 strips. That's 9 rolls.
Why square-foot estimates fall short
A roll's printed coverage assumes you use every inch, but in practice the leftover piece at the end of each roll is usually too short for another strip, and pattern matching wastes more. Counting strips avoids coming up one roll short.
Hanging tips
- Check every roll's batch number before you start, and keep one spare roll from the same batch.
- Start in a corner that's least noticeable, because the last strip rarely matches the first perfectly.
- Use a level or plumb line for your first strip. Walls and corners are rarely perfectly straight.
- Prime bare drywall with a wallpaper primer so the paper can be removed later without damaging the wall.
Frequently asked questions
How many rolls of wallpaper do I need for a room?
Work out how many full-height strips go around the room (wall length ÷ roll width), then how many strips you can cut from one roll (roll length ÷ strip length). Divide the first by the second and round up. A 12 × 12 ft room with 8 ft walls, one door and one window needs about 9 rolls of 20.5 in × 33 ft paper with no pattern repeat.
What is a pattern repeat?
It's the vertical distance before the pattern starts over. Every strip has to line up with the one beside it, so each strip may need to be up to one repeat longer than the wall height. Large repeats can noticeably increase how many rolls you need.
What size is a roll of wallpaper?
Many rolls sold in the US are 20.5 or 21 inches wide and about 33 feet long (sold as a double roll covering about 56 sq ft). European rolls are 53 cm wide and 10.05 m long. Check the label, because sizes vary.
Should I subtract doors and windows?
Subtract doors, because they take out full-height strips. For windows, you still need short strips above and below, so the calculator only takes off half a window's width.
Why buy all the rolls at once?
Each production run, called a batch or dye lot, can differ slightly in color. Buying all your rolls from the same batch, plus one spare, avoids visible differences between strips.