12 × 10 ft room, 8 ft walls, 1 door, plain paper
24 strips, 3 strips per roll, 8 rolls of 20.5 in × 33 ft.
Wallpaper calculator
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Wallpaper is hung in full-height strips with 4 inches extra per strip for trimming. Each door takes away 3 ft of wall width; windows are not deducted, because you still need paper above and below them.
ft
ft
ft
Roll size
inches
Printed on the label. Use 0 for a plain paper.
Rolls of wallpaper
8
24 strips of 8 ft cover 41 ft of wall. Each roll gives 3 strips. Buy all rolls from the same batch number.
- Strips needed
- 24
- Strips per roll
- 3
- Wall area
- 328 sq ft
Rolls by pattern repeat
| Pattern repeat | Strips per roll | Rolls |
|---|---|---|
| None | 3 | 8 |
| 6 in | 3 | 8 |
| 12 in | 3 | 8 |
| 18 in | 3 | 8 |
| 24 in | 3 | 8 |
How decorators count wallpaper
Wallpaper is hung in vertical strips, each the full height of the wall. The part left at the end of a roll is usually too short for another strip, so working from area alone tends to leave you a roll or two short. Counting strips is more reliable.
Take a 12 × 10 ft room with 8 ft walls and one door. The walls run 44 ft round, and the door takes away 3 ft, leaving 41 ft. Standard rolls are 20.5 inches wide, so that is 24 strips. Each strip needs 8 ft plus 4 inches for trimming, and a 33 ft roll gives 3 such strips. So you need 8 rolls.
A pattern repeat adds waste, because each strip has to start at the same point in the pattern. With a large repeat on a taller wall you may get only two strips from a roll, which raises the count a lot. The table shows how the number of rolls changes with the repeat.
Buy every roll from the same batch, and keep one spare. A repair years later is much easier if you have a matching piece.
Sources
What this calculator does not account for
- Windows are not deducted.
- Uses one wall height for the whole room.
How this is calculated
Formula: The strip method
rolls =round up(strips needed ÷ strips per roll)What the symbols mean
- strips neededWall width to cover ÷ roll width, rounded up.
- strips per rollRoll length ÷ (wall height + pattern repeat + 4 in trim), rounded down.
Good to know
- Each door takes off 3 ft of width. Windows are not taken off.
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Worked examples
Each example is worked out by the same code as the calculator above.
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<iframe src="/embed/wallpaper-calculator" title="Wallpaper calculator" width="100%" height="720" style="border:0;max-width:42rem" loading="lazy"></iframe>Questions
How many rolls of wallpaper for a 12 × 10 ft room?
With 8 ft walls, one door and a plain paper on standard 20.5 in × 33 ft rolls, 8 rolls.
What is a pattern repeat?
The height after which the design repeats. Each strip has to be shifted to line the pattern up, which wastes some paper.
Why not just divide the wall area by the roll area?
Because leftover pieces from the end of a roll are usually too short to use. Counting full strips avoids running short.
Should I buy an extra roll?
Yes, from the same batch. Colours can differ between batches.
Do I deduct windows?
Usually not. You still need paper above and below them, and the offcuts rarely save a whole roll.