Wallpaper Calculator
Count wallpaper rolls from full-height drops and pattern repeat.
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What this tool does
Count wallpaper rolls from full-height drops and pattern repeat. Windows are not deducted because full drops are usually still cut; match type may add extra waste.
How to use the Wallpaper Calculator
- Enter or select wall perimeter in ft.
- Enter or select wall height in ft.
- Enter or select roll width in in.
- Enter or select roll length in ft.
- Enter or select pattern repeat in in.
- Enter or select trim per drop in in.
- Read the calculated result; change any measurement to compare alternatives.
Formula
dropLength=repeat>0?ceil((height×12+trim)/repeat)×repeat:height×12+trim; drops=ceil(perimeter×12/rollWidth); dropsPerRoll=floor(rollLength×12/dropLength); rolls=ceil(drops/dropsPerRoll)
- perimeter
- Wall perimeter (ft, before metric conversion)
- height
- Wall height (ft, before metric conversion)
- rollWidth
- Roll width (in, before metric conversion)
- rollLength
- Roll length (ft, before metric conversion)
- repeat
- Pattern repeat (in, before metric conversion)
- trim
- Trim per drop (in, before metric conversion)
Windows are not deducted because full drops are usually still cut; match type may add extra waste.
Worked example
For wallpaper calculator, the following measurements illustrate the exact method: Wall perimeter: 64; Wall height: 8; Roll width: 20.5; Roll length: 33; Pattern repeat: 12; Trim per drop: 4.
Inputs
- Wall perimeter64 ft
- Wall height8 ft
- Roll width20.5 in
- Roll length33 ft
- Pattern repeat12 in
- Trim per drop4 in
Result
- Rolls to buy13
- Drops per roll3
- Cut length per drop108 in
Results explained
- Rolls to buy
- Rolls to buy from the formula above. Windows are not deducted because full drops are usually still cut; match type may add extra waste.
- Drops per roll
- Drops per roll from the formula above. Windows are not deducted because full drops are usually still cut; match type may add extra waste.
- Cut length per drop
- Cut length per drop from the formula above, expressed in in before metric conversion. Windows are not deducted because full drops are usually still cut; match type may add extra waste.
Frequently asked questions
Round each drop to the next pattern repeat, then count whole drops per roll.
Measure perimeter, wall height, roll width/length and repeat.
Use 5–10% for simple layouts and 10–15% for diagonal cuts or complicated outlines; the allowance is editable.
Split the outline into rectangles or triangles and calculate each section separately. Do not count overlapping sections twice.
This is a purchasing estimate, not a structural design. Confirm measurements and local requirements before buying or building.