Everyday
Wallpaper Calculator
Count wallpaper rolls the right way: drops cut one pattern repeat long, so the design lines up.
How it works
Behind the numbers
A drop is the strip that runs floor to ceiling. To keep the design aligned, each drop is cut to the wall height plus one full pattern repeat, because the matching point can fall anywhere in the repeat. With a 12-inch repeat on an 8 ft wall, each drop is cut 9 ft long, not 8. Calculators that ignore the repeat undercount rolls on every patterned paper.
Strips per roll is the roll length divided by the cut length, rounded down. Drops per wall is the wall width divided by the roll width, rounded up. Total rolls is total drops divided by strips per roll, rounded up. A 12 ft wall with a 20.5-inch-wide, 33 ft roll and a 12-inch repeat needs 8 drops at 3 strips per roll, which is 3 rolls.
Waste is computed from the cutting plan: the paper area in the rolls minus the wall area, divided by the wall area. Patterned papers typically show 30 to 70 percent cutting waste, which surprises buyers used to paint math. Enter 0 for the repeat with plain or random-match papers.
FAQ
Questions, answered
How many rolls of wallpaper do I need?
Divide the wall into drops (wall width divided by roll width, rounded up), then divide drops by the strips each roll yields. A 12 ft wall with a standard 20.5 in by 33 ft roll and a 12 in pattern repeat needs 8 drops at 3 strips per roll, so buy 3 rolls.
What is pattern repeat and why does it change the roll count?
The pattern repeat is the vertical distance before the design starts over, printed on the roll label. Each drop must be cut one full repeat longer than the wall so the pattern lines up at the ceiling, which shortens how many strips a roll yields. Ignoring it is the most common reason online estimates come up short.
How much wallpaper waste should I expect?
Cutting waste on patterned wallpaper often runs 30 to 70 percent, much higher than paint, because every drop carries an extra repeat and offcuts rarely fit the next wall. The calculator shows the exact waste from your cutting plan instead of asking you to guess a percentage.
What if my wall is taller than the roll is long?
Then each drop needs a vertical join and consumes a full roll. The calculator flags this case and counts one roll per drop. Check the roll label first: a standard US double roll is 33 ft long, a European roll 10.05 m.