Wallpaper Roll Calculator
Dye lots don't match between orders, so running one roll short means re-papering a wall. Enter your walls, your roll size, and the pattern repeat, and get the roll count that accounts for strips, trim, and match waste.
Uses the full perimeter. For a feature wall, set length and width to give the run you're papering.
0 for a random/free match. Otherwise the vertical distance the pattern repeats — on the roll's label.
Advanced: trim, waste & price
Formula & how it works
Strip length = wall height + trim, rounded up to a whole pattern repeat. Strips per roll = roll length ÷ strip length (rounded down). Strips needed = wall perimeter ÷ roll width (rounded up).
Rolls = strips needed ÷ strips per roll, rounded up, then a waste margin is applied and rounded up again.
Worked example
A 12 × 12 room, 8-ft walls: perimeter 576″. With a 20.5″ × 33-ft roll and a 19″ repeat, strips are 114″ long, so 3 strips per roll. You need 29 strips ÷ 3 = 10 rolls, and 10% waste rounds to 11 rolls.
Buying wallpaper
Dye lots are the real risk
Color can shift subtly between print runs, so a roll bought later may not match. Order every roll at once from the same lot and keep the labels until the job is finished and you're sure you have enough.
Big repeats cost more paper
A large pattern repeat forces each strip to a taller whole-repeat length, and the offcut is usually wasted. If two papers are close, the one with the smaller repeat will stretch further across the same wall.