Wallpaper Roll Calculator
Wallpaper is hung in vertical strips, so the count depends on how many strips your walls need and how many full strips you can cut from one roll. The strips needed come from the wall perimeter divided by the roll width. The strips per roll come from the roll length divided by the cut length, where the cut length is the wall height rounded up to the next pattern repeat. This calculator combines both, rounding up to whole rolls. Roll sizes and repeats vary by product, so enter the values printed on your wallpaper label.
Wallpaper roll formula
Strips needed = ceil(perimeter (in) / roll width (in))
Cut length = repeat > 0 ? height rounded up to next repeat : height
Strips per roll = floor(roll length / cut length)
Rolls = ceil(strips needed / strips per roll)
Cutting each strip to a whole number of pattern repeats lets the design line up across seams. A bigger repeat raises the cut length and can cost you a usable strip per roll. Lengths are converted to consistent units before dividing.
Wallpaper context
- Wallpaper hangs in vertical strips, so strip count is driven by wall perimeter and roll width.
- The pattern repeat sets how much you round each strip up for matching, increasing waste.
- Partial strips left on a roll usually cannot be used at full wall height.
- Buy all rolls from one batch (lot) number so the color matches across the wall.
- Order a little extra for trimming, mistakes, and future repairs.
Wallpaper rolls: frequently asked questions
How many rolls of wallpaper do I need?
Work out how many full-height strips your walls need (wall perimeter divided by roll width), then how many strips you get from each roll (roll length divided by the cut length per strip). Divide strips needed by strips per roll and round up. Add an allowance for the pattern repeat and waste at the top and bottom of each strip.
What is the pattern repeat?
The pattern repeat is the vertical distance over which the design repeats. To match the pattern across strips you must cut each strip to the wall height rounded up to the next whole repeat, so a large repeat wastes more paper. Straight-match and drop-match repeats behave differently, but both increase the cut length per strip.
How do I find usable strips per roll?
Divide the roll length by the cut length per strip and round down to a whole number, because a partial strip at the end of a roll usually cannot be used full height. With a long repeat the cut length grows and you may get one fewer usable strip per roll, which is why repeat matters.
Should I subtract doors and windows?
For small rooms many hangers do not subtract openings, treating the offcuts as spare for matching and mistakes. For large openings you can reduce the perimeter, but keep a margin. This calculator works from the perimeter you enter, so you can decide how much opening area to deduct.
Why buy from the same batch?
Wallpaper is printed in batches (also called lots or runs), and color can vary slightly between batches. Buy all your rolls from one batch number and order a little extra, because a later top-up roll from a different batch may not match exactly on the wall.
Official sources
- U.S. National Institute of Standards and Technology: NIST Unit Conversion (length units).
- International Code Council: International Residential Code (interior finishes).
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.