Wallpaper roll calculator
Estimate wallpaper strips and whole rolls with pattern repeat; a 4 m wall, 2.5 m high, 0.53 m rolls of 10.05 m and a 0.64 m repeat need 3 rolls.
- Runs in your browser
- No upload
- Instant result
Quantity estimate only. This does not approve structural safety, load capacity, drainage, fire resistance or building-code compliance. Verify the design and local requirements with a qualified professional. Purchase quantities round up to whole packs.
Assumptions & formula
Formula and assumptions
w = Waste allowance/100; n=ceil(W/rollWidth); d=ceil((H+trim)/repeat)repeat; k=floor(rollLength/d); N=ceil(Σ(q×ceil(n/k))(1+w))
Enter each wall as width height quantity. This is a straight-match full-drop estimate. Pattern repeat rounds each drop length up. Openings reduce reported net area but do not remove full drops or reduce rolls. Each wall is rounded separately; offcuts are not reused. Half-drop and complex matches need a separate cutting plan.
The prefilled values are editable examples, not product specifications. Enter your supplier’s yield, density, coverage and packaging values, and add an allowance for overlaps, compaction and cuts where needed.
Purchase counts use the exact entered decimals and unit factors, without a rounding tolerance that could discard a real remainder. π and irrational square roots use enclosing bounds; ambiguous counts produce an error. Counts must be safe integers.
Results
Enter values and press Calculate to see the result here.
How to use this calculator
- Set inputs and units
Enter each wall’s width and height, the roll dimensions, the pattern repeat and the trim. A third number in a row repeats that whole wall.
- Calculate
Check this worked example: wall4×2.5 m,opening1×1 m,roll0.5×10 m,repeat0.5 m,trim0.1 m,waste0% →net9 m²,drops8,rolls3
- Results
The cut length is rounded up to the repeat. The number of full drops per roll decides what you buy, not the net area alone.
Questions and limits
Do windows remove wallpaper drops?
No. Openings affect the net area reported, but they don't remove full-height drops. This cautious model doesn't reuse offcuts across openings.
Which input errors should I correct?
A repeat-rounded drop must fit on one roll. Make sure the trim is the total length added to each drop, not a per-end value in another unit.
What does this calculation leave out?
No sharing of offcuts between walls, no optimization of half-drop matching and no layout guarantee for a particular installer.