About this calculator
This calculator helps estimate how many wallpaper rolls a wall needs — enter the wall dimensions, the roll width and length, and the pattern repeat step (if the wallpaper has a pattern that needs matching). Useful for planning a room or corridor wallpapering job.
Formula
The calculator converts the wall and roll dimensions to whole millimetres, then:
one strip's cut length = wall height + pattern repeat
strips per roll = floor(roll length / strip length)
strips required (excl. waste) = ceil(wall length / roll width)
waste strips = ceil(strip count × waste% / 100)
total strips = strip count + waste strips
rolls required = ceil(total strips / strips per roll)
The pattern repeat is added to each strip's length so the pattern can be aligned at the top of every strip — for plain wallpaper with no pattern this value is 0, and the strip length simply equals the wall height. If the wall height plus the pattern repeat exceeds the roll length, the calculator returns an error — not a single full strip could be cut from such a roll.
Worked example
Defaults: wall length 4 m, height 2.5 m, no openings, roll width 530 mm, roll length 10.05 m, pattern repeat 0 mm, waste 15%.
strip length = 2500 mm + 0 mm = 2500 mm
strips per roll = floor(10,050 / 2500) = floor(4.02) = 4
strips excl. waste = ceil(4000 / 530) = ceil(7.55) = 8
waste strips = ceil(8 × 15 / 100) = 2
total strips = 8 + 2 = 10
rolls required = ceil(10 / 4) = 3
For these inputs the calculator returns exactly this: 10 strips total, 4 strips per roll, and 3 rolls.
FAQ
Are openings (doors, windows) deducted from the strip quantity? No. Unlike the wall-tile or plaster calculators, strip count here is deliberately computed as if the wall had no openings — strips are bought and hung across the full wall height, and a strip crossing a window is still cut to its full length (the part covering the window becomes waste, not a saved strip). This is because the calculator doesn't collect an opening's horizontal position on the wall, so it can't know whether an opening exactly replaces one particular strip. Opening area is shown only in the informational "net area" field.
Why do I need to enter a pattern repeat? If the wallpaper has a pattern, each strip's start needs to align with the previous one — that means a bit more than exactly the wall height is cut from the roll. For plain wallpaper with no pattern, leave this at 0.
How much waste should be allowed for hanging wallpaper? The default is 15%, adjustable from 0 to 50. Pattern matching, corner cutting, and strip overlap at corners typically need more waste than a plain wallpaper with no pattern.
What does the error about a too-short roll mean? If the wall height plus the pattern repeat exceeds the whole roll length, not one full strip can be cut from such a roll — you'd then need either a shorter wall or a different, longer roll.
What determines the roll dimensions and waste percentage? Roll width, length, and pattern repeat are values you enter — they're printed on your specific chosen wallpaper's packaging, so the calculator doesn't derive them from any standard or universal constant.
Assumptions and limits
No standard was found for roll dimensions, pattern matching, or waste rate — these depend on
the specific product and pattern, so meta.standards is deliberately left empty.
Openings are not deducted from the strip count. This is a deliberate, conservative decision: wallpaper is hung in full strips across the whole wall height, and a strip over or around a window is still cut to its full length — the part covering the window becomes waste, not saved material. Since the calculator doesn't collect an opening's horizontal position on the wall, it can't know whether an opening exactly matches one strip's width — skipping a strip without that information would risk buying too little, which is exactly what this calculator aims to avoid. Opening area is shown only as an informational "net area" value, with no effect on strip or roll count.
Roll width, length, pattern repeat, and waste percentage are user inputs with example (not product-specific) defaults — your chosen wallpaper's exact figures must be entered.
The drawing is schematic: for a very wide wall or a narrow roll, the strip-line count is decimated so the SVG stays legible, and openings are drawn spread evenly across the wall length, since the calculator doesn't collect their exact position.