Calculate the wallpaper roll quantity needed based on room perimeter, height, roll size and pattern repeat — with margin.
| Step | Formula |
|---|---|
| Strip length | height, rounded up to the nearest pattern repeat multiple (if repeat > 0) |
| Strips / roll | roll length ÷ strip length (rounded down) |
| Strips needed | room perimeter ÷ roll width (rounded up) |
| Rolls needed | strips needed ÷ strips/roll × (1 + margin %), rounded up |
It's recommended to keep 1 extra roll in reserve for future repairs — color/batch may differ if bought later.
The distance after which the wallpaper pattern repeats vertically. When cutting strips, extra length must be left so the pattern matches between adjacent strips — this increases waste.
The calculator works on the full perimeter — this gives a small margin for window/door areas, which usually don't need a full strip.
10–15% is standard, for complex pattern matching (large repeat) — up to 20%.
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