Wallpaper Calculator
Estimate how many rolls of wallpaper a room needs from the wall area, the roll size and an allowance for pattern matching.
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Formula and method
Total wall area is reduced by the openings area, multiplied by the waste allowance and divided by the coverage of one roll. The result is rounded up because rolls are sold whole.
Rolls are sold by area but decided by drops
A standard roll is 0.53 m wide and 10 m long, about 5.3 m², but you cannot use the last part of a roll that does not fit a full drop. A 2.7 m wall gives three drops per roll with 1.9 m left over, which is waste unless the pattern repeat is small enough to continue. That is why a room of 45 m² of wall can need eleven rolls rather than nine.
Pattern repeat makes it worse. A 64 cm straight match on a 2.7 m drop costs an extra 0.64 m per drop, and an offset match costs more because alternate drops shift by half the repeat. The calculator's roll count comes from drops per roll, so the repeat field is the one to fill honestly.
Lining paper, paste and the wall behind
Lining paper is a separate quantity: it smooths a wall that is structurally sound but visually rough, and it is cheaper than the finishing paper it protects. A wall that has been stripped of old paper needs it, a new plaster wall needs it, and a wall painted with gloss needs it or the paste will not hold.
Paste is sold by the roll and the rate depends on the paper: non-woven papers want paste on the wall, paper-backed ones want it on the paper, and a heavy vinyl wants both. One tub usually covers six to eight rolls, which is a line item people forget until the first drop is already on the wall.
Corners, reveals and the spare roll
Every corner, window reveal and door frame adds cutting waste that is not proportional to area. A rectangular room with two windows needs about 10 % more than the arithmetic suggests; a room with five corners, a chimney breast and a bay needs 15 %.
Keep one spare roll from the same batch. Wallpaper batches differ in colour, and a repaired strip from a later batch is visible in daylight even when the pattern matches. One roll costs less than repapering a wall.
How to measure the inputs
- Measure the total wall length to cover and the wall height, then count how many walls are the same.
- Add up the area of doors and windows you want to deduct.
- Read roll length and usable width from the roll label; 10.05 m × 0.53 m is a common size.
Worked example
Wall length 26.25 ft; Wall height 8.2 ft; Wall count 3; Openings area (optional) 12.92 ft²; Roll length 34.45 ft; Roll width 1.74 ft; Waste 10 % → Rolls required: 12
Reference data
| Perimeter, m | Rolls 0.53 × 10 m | Rolls 1.06 × 10 m |
|---|---|---|
| 12 | 8 | 4 |
| 16 | 11 | 6 |
| 20 | 13 | 7 |
| 24 | 16 | 8 |
Ceiling 2.7 m with no pattern repeat: three strips per roll. A repeat costs one extra roll per room.
Practical tips
- Order all rolls from the same batch — printed batch numbers must match.
- Cut and hang one wall at a time so pattern alignment stays under control.
- Keep one spare roll in case of later damage.
Sources
- EN 233 — Wallcoverings in roll form
Checked and updated October 22, 2026