Wallpaper Calculator
A wallpaper calculator counts the strips your walls need, then fits those strips onto rolls. Enter wall sizes, roll size and pattern repeat. A 12 by 12 foot room with 10 foot ceilings needs 11 rolls of 20.5 inch by 33 foot paper, or 16 rolls when the pattern repeats every 24 inches.
This tool is part of our area calculators. Use it for a whole room or for a single wall.
- Updated October 2026
- Sources Cited
- No Login Required
- Free to Use
Wallpaper Strip Planner
Rolls to buy
11 rolls
20.5 in x 33 ft each, 620.13 sq ft bought
- Strips (drops)
- 32
- Drop length
- 100 in
- Strips per roll
- 3
- Left over
- 236.13 sq ft
Your walls need 32 strips of 100 in. One roll yields 3 strips, so you need 11 rolls.
Area method for the same walls: 7 rolls. Area math assumes you can use every inch of every roll. You cannot, because strips are cut to wall height and each wall rounds up to whole strips.
| Wall | Size | Drop (in) | Strips |
|---|---|---|---|
| 1 | 12 ft wide x 8 ft high | 100 | 8 |
| 2 | 12 ft wide x 8 ft high | 100 | 8 |
| 3 | 12 ft wide x 8 ft high | 100 | 8 |
| 4 | 12 ft wide x 8 ft high | 100 | 8 |
| Roll size | Strips | Per roll | Rolls |
|---|---|---|---|
| 20.5 in x 33 ft | 32 | 3 | 11 |
| 27 in x 27 ft | 24 | 3 | 8 |
| 20.9 in x 32.8 ft | 28 | 3 | 10 |
This is an estimate. Windows and doors are not deducted unless you remove strips above. Buy all rolls in one order so they come from the same dye lot, and confirm roll size and repeat with your supplier.
Strips per wall
Each wall rounds up on its own, the way paper is hung.
Pattern repeat
Straight, half-drop and random match change the strip length.
Area method beside it
See the lower area-method figure and why it under-orders.
Estimates are for material planning. Check the roll size, length and repeat on your paper's label before you order, and buy every roll from one dye lot.
How to calculate how many wallpaper rolls you need
Measure each wall's width and height. Add about 4 inches to each height for trim. Divide each wall's width by the roll width and round up to get strips. Divide the roll length by the strip length and round down to get strips per roll. Divide total strips by strips per roll and round up.
- Measure each wall in inches. The calculator takes feet and inches.
- Add the trim allowance to the height. The default is 4 inches, top and bottom combined.
- Round the strip length up to a multiple of the pattern repeat, if the paper has one.
- Count strips per wall, then drops per roll, then rolls.
If you only have floor dimensions, start from our square footage calculator to check wall area. The strip count still needs each wall's own width.
Worked example: a 12 by 12 foot room
A 12 by 12 foot room with 8 foot ceilings has four walls of 144 inches. Each wall needs 8 strips of 20.5 inch paper, so the room needs 32 strips. Each strip is 100 inches with trim. A 33 foot roll yields 3 strips, so the room needs 11 rolls. Area math gives only 7 rolls.
| Room | Roll | Repeat | Strips | Drop (in) | Drops per roll | Rolls | Area method |
|---|---|---|---|---|---|---|---|
| 12 x 12 ft, 8 ft ceilings | A | None | 32 | 100 | 3 | 11 | 7 |
| 12 x 12 ft, 8 ft ceilings | A | 24 in straight | 32 | 120 | 3 | 11 | 7 |
| 12 x 12 ft, 10 ft ceilings | A | None | 32 | 124 | 3 | 11 | 9 |
| 12 x 12 ft, 10 ft ceilings | A | 24 in straight | 32 | 144 | 2 | 16 | 9 |
| 12 x 12 ft, 10 ft ceilings | A | 24 in half-drop | 32 | 144 | 2 | 16 | 9 |
| 10 x 12 ft, 8 ft ceilings | A | None | 28 | 100 | 3 | 10 | 7 |
| 12 x 12 ft, 8 ft ceilings | B | None | 24 | 100 | 3 | 8 | 7 |
| 12 x 12 ft, 8 ft ceilings | C | None | 28 | 100 | 3 | 10 | 7 |
Rolls A, B and C are listed in the roll sizes section. Trim is 4 inches. In the half-drop row the first strip is 144 inches and later strips are 156 inches.
How pattern repeat adds rolls
Pattern repeat is the vertical distance between identical points in the design. Each strip must start at the same point in the pattern, so strip length rounds up to a multiple of the repeat. At 10 foot ceilings, a 24 inch repeat lengthens each strip from 124 to 144 inches. A 33 foot roll then yields 2 strips, not 3.
A half-drop pattern shifts each neighboring strip by half a repeat. The rule from the DecoratorsBest glossary is to add half the repeat to every drop except the first. A random match has no repeat to line up, so it needs no rounding.
| Repeat (in) | Drop (in) | Drops per roll | Rolls |
|---|---|---|---|
| None | 124 | 3 | 11 |
| 12 | 132 | 3 | 11 |
| 18 | 126 | 3 | 11 |
| 24 | 144 | 2 | 16 |
| 36 | 144 | 2 | 16 |
Why area math under-orders
Dividing wall area by roll area assumes you can use every inch of the roll. You cannot. A 33 foot roll cut into 100 inch strips leaves 96 inches unused. Strips also round up at each wall. For the 12 by 12 foot room above, area math gives 7 rolls and the strip method gives 11.
The area method works as a quick check. Net wall area is 2 x (12 + 12) x 8 = 384 square feet. One roll of 20.5 by 396 inches is 56.375 square feet, and 384 divided by 56.375 is 6.8. The calculator shows that figure beside the strip result so you can see the gap.
Single, double and European roll sizes
A typical US single roll covers 28 to 35 square feet, and a double roll covers 56 to 70. Many US makers price by the single roll and ship double rolls. A European roll is about 20.9 inches by 32.8 feet, or 57 square feet. Check the label, because there is no universal single roll size.
| Preset | Size | Area (sq ft) | Source |
|---|---|---|---|
| A | 20.5 in x 33 ft | 56.4 | DecoratorsBest glossary (Euro roll, 20.5 in, 11 yd) |
| B | 27 in x 27 ft | 60.8 | DecoratorsBest glossary (two 4.5 yd single rolls of 27 in) |
| C | 20.9 in x 32.8 ft | 57.1 | Selected Wallpapers (European roll, 53 cm x 10 m) |
The two sources disagree on the term "Euro roll", so both sizes are kept as separate presets. Use the custom roll for any other size.
Doors, windows and spare rolls
Sources disagree on openings. Thibaut advises against deducting doors and windows, and Omni Calculator deducts them. This calculator counts whole strips, so it subtracts nothing by default. Enter the number of strips a wide opening removes in the opening strips field.
Waste comes from the layout: trim, repeat rounding and the offcut at the end of each roll. The spare allowance is optional and starts at 0 percent. Omni suggests 10 percent extra and Thibaut up to 20 percent extra for complex fits.
Buy every roll in one order. Lots made at different times can vary slightly in color, so rolls from one dye lot hang better together.
Square feet, yards and square meters
One square foot equals 0.0929 square meters. One square meter equals about 10.76 square feet. Five yards of paper is 15 feet long. At 27 inches wide it covers 33.75 square feet. At 20.5 inches wide it covers 25.63 square feet.
| From | To |
|---|---|
| 1 square foot | 0.0929 square meters |
| 1 square meter | 10.764 square feet |
| 1 yard | 3 feet |
| 5 yards, 27 in wide | 33.75 square feet |
| 5 yards, 20.5 in wide | 25.63 square feet |
What this calculator does not cover
This page counts rolls of paper. It does not give paint gallons, so use the paint calculator for that. Murals are printed to the wall size and have no roll math. The tool does not plan ceilings or borders, does not cover removal, and shows no prices or paste amounts.
Inputs are in feet and inches. Metric input is not built yet.
Methodology and sources
Published October 2026. Last updated October 2026. Next review October 2027.
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Rachel Torres is a construction education specialist holding an M.Ed. and NCCER Master Trainer certification (#MT-2018-4492). With 14 years bridging field engineering at Kiewit Infrastructure and classroom instruction, she writes CalcSummit's conversion calculators, educational guides, and glossary content to NCCER and ICC curriculum standards. She developed the 'Construction Math Made Simple' course used by ACTE member programs.
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