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Wallpaper Calculator

Find how many rolls of wallpaper you need, counted strip by strip with the pattern repeat.

  • Reviewed October 2026
  • Formula and worked example below
  • Free, no sign-up, runs in your browser
ft
For a whole room, add up all wall widths (the room perimeter).
ft
Each door saves about 3 ft of width.
in
Printed on the label; 0 for random-match papers.
in
ft
A US double roll is about 20.5 in × 33 ft; a European roll is 21 in × 33 ft (0.53 × 10.05 m).
Enter your numbers to see the result.

How many rolls of wallpaper do I need?

Wallpaper is hung in vertical strips, so counting strips is more accurate than dividing square feet. Each strip is the wall height plus the pattern repeat plus about 4 in for trimming.

Strips = Wall width ÷ Roll width · Strips per roll = Roll length ÷ Strip length (whole strips only) · Rolls = Strips ÷ Strips per roll

A 12 × 12 ft room has 48 ft of wall. Leaving out one 3 ft door, 540 in of wall ÷ 20.5 in rolls = 27 strips. With 8 ft walls each strip is 100 in, so a 33 ft (396 in) roll gives 3 full strips: 9 rolls.

Windows are not deducted, because strips above and below a window are short offcuts that rarely save a full roll. Buy one extra roll from the same batch number: later batches can differ slightly in color.

Single rolls and double rolls

In the US, wallpaper is often priced per single roll but sold only in double rolls. A double roll of about 56 ft² is what most brands ship. Enter the actual dimensions from the label to be sure.

Pattern repeat

A straight-match pattern lines up across strips at the same height; a drop match shifts by half the repeat. Either way, budget one full repeat per strip. Large repeats (21 in or more) can increase the number of rolls by a third.

Frequently asked questions

How many rolls of wallpaper for a 12×12 room?

With 8 ft ceilings and standard 20.5 in × 33 ft double rolls, about 9 rolls for a random match and more for large pattern repeats.

How much does a roll of wallpaper cover?

A US double roll covers about 56 ft², but usable coverage is lower after trimming and matching, often 45–50 ft².

Should I subtract windows?

Subtract doors and very large windows only. Small window cut-offs are rarely usable.

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Last reviewed October 2026. Results are estimates; check important decisions with a qualified professional.