Formula used
Units = ceil([project area ÷ coverage per unit] × [1 + waste ÷ 100])
Worked wallpaper example
Wallpaper Calculator example: 619 ft² × 1.1 = 680.9 ft² of order coverage. Dividing by 100 ft² per unit gives 6.81 units, so the purchase quantity is 7 whole units.
Package rounding and usable yield
Round to whole rolls from the same batch and verify the strip layout; area-only math is least reliable for large pattern repeats.
Usable roll coverage depends on the pattern
Published roll area can overstate usable wall coverage when each strip must be cut to wall height and advanced to the next pattern match. Use a coverage figure that accounts for roll width, wall height, pattern repeat, drop match, trimming, and damaged ends. Calculate rooms with different heights or patterns separately.
Why the label value may not match the floor or wall
Roll width and length, straight or drop match, repeat size, wall height, batch number, windows, and damaged strips govern real yield.
Questions specific to this calculation
What usable coverage should I enter for wallpaper?
Measure wall area, then replace the generic coverage field with the usable coverage of the selected roll after pattern repeat and trimming are considered.