Wallpaper Calculator
Wallpaper rolls needed depends on the room's total wall area and how much one roll actually covers — with a buffer added for pattern matching and trimming, since exact-fit ordering rarely works out in practice.
Inputs
Result
10 rolls
Wall area 45 m² (incl. 10% extra)
How the wallpaper calculator works
Wall area = room perimeter × wall height.
Rolls needed = (wall area ÷ roll coverage) × 1.1, rounded up to a whole roll, with the 1.1 factor building in a 10% allowance for trimming and pattern matching.
Worked example: 18 m perimeter, 2.5 m height, 5 m² roll coverage
- Wall area = 18 × 2.5 = 45 m².
- Rolls = (45 ÷ 5) × 1.1 = 9 × 1.1 = 9.9, rounded up to 10 rolls.
Common mistakes to avoid
Forgetting to subtract door and window area for a more precise estimate
This calculator uses gross wall area (perimeter × height) without subtracting doors and windows — for a room with large windows or multiple doors, the true wallpaper need is somewhat less than this calculation suggests, though the built-in 10% buffer often absorbs small differences.
Using coverage figures from a different-sized roll than what's actually being purchased
Roll coverage varies by brand, width and length — always use the specific product's stated coverage area rather than a generic assumption, since standard roll sizes differ between regions and manufacturers.
Frequently asked questions
Why is a 10% buffer built directly into this calculation?
Pattern-matched wallpaper especially wastes material aligning repeats across roll widths, and any wallpapering job involves trimming at ceiling and floor edges — 10% is a standard practical allowance for both.
Should I subtract door and window area before entering the perimeter and height?
For a more precise (usually lower) estimate, yes — subtract the combined door/window area from the calculated wall area separately, keeping in mind the built-in buffer already covers some of this margin.
Do patterned wallpapers need more rolls than plain ones?
Often yes — large repeat patterns can require extra material to align matches between drops, sometimes needing an allowance beyond the standard 10% built into this calculator.
How does roll coverage vary between wallpaper types?
Standard and 'double' or 'triple' rolls have different total areas depending on the manufacturer and region — always check the specific coverage stated on the product rather than assuming a universal figure.
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