Wallpaper is sold by the roll, and the label gives its width and length. A common US double roll, also called a bolt, is 20.5 in wide and 33 ft long. Many US sidewall papers are priced per single roll but sold as double rolls, so check what a price covers. A standard European roll is 0.53 m wide and 10 m long.
How to use this calculator
- Measure the room's length and width at the floor, and the wall height from the floor to the ceiling. Use the tallest height, so that no strip falls short.
- Pick the roll type that matches your label: US double roll or European roll.
- Enter the pattern repeat in inches or centimetres, from the label or the maker's website. For a plain or random pattern, leave it at its starting value.
- Enter the width of doors and windows under More options only if you want them taken off the wall run.
- If you plan to trim each strip at the top and bottom, enter a taller wall height. Buy every roll in one order, since print runs can vary in shade.
Worked examples
Bedroom, plain pattern
Size: 12 × 14 ft · Wall height: 8 ft · Pattern repeat: 0 in
- Rolls
- 8 double rolls
- Strips
- 31
- Strips per roll
- 4
- Strip length
- 8.00 ft
Bedroom, large pattern repeat
Size: 12 × 14 ft · Wall height: 8 ft · Pattern repeat: 24 in
- Rolls
- 11 double rolls
- Strips
- 31
- Strips per roll
- 3
- Strip length
- 10.00 ft
Square room with European rolls
Size: 12 × 12 ft · Wall height: 8 ft · Roll type: European roll · Pattern repeat: 0 in
- Rolls
- 7
- Strips
- 28
- Strips per roll
- 4
- Strip length
- 8.00 ft
Small powder room
Size: 5 × 6 ft · Wall height: 8 ft · Pattern repeat: 0 in
- Rolls
- 4 double rolls
- Strips
- 13
- Strips per roll
- 4
- Strip length
- 8.00 ft
US double rolls for common room sizes at each pattern repeat
| Room | Pattern repeat: 0 in | Pattern repeat: 12 in | Pattern repeat: 24 in |
|---|---|---|---|
| 10 × 10 ft | 6 | 8 | 8 |
| 12 × 12 ft | 8 | 10 | 10 |
| 12 × 14 ft | 8 | 11 | 11 |
| 15 × 18 ft | 10 | 13 | 13 |
Each cell: Rolls (double rolls). Inputs not in the table use the calculator's starting values.
How the strip method works
The calculator starts with the wall run, which is the room's length and width added together and doubled. Dividing it by the roll width gives the strips, rounded up, because a partial strip still has to be cut.
Each strip is cut to the wall height plus a full pattern repeat, so the design lines up. Only whole strips come off a roll, so the calculator divides the roll length by the strip length and rounds down. The strips needed, divided by that, rounded up, give the rolls to buy.
That is why the calculator counts rolls rather than square feet: the piece left at the end of each roll is waste. A European roll is a little wider, so the same walls can need fewer strips.
Pattern repeat and why it adds a roll
The pattern repeat is the distance down the wall before the design starts again. Plain and random papers have none. Leaving the repeat out of a patterned paper gives a count that is too low, because the strips come out too short to match.
Each strip grows by the full repeat, so each roll holds fewer whole strips, and a repeat can add a whole roll to the same room. The count moves in steps, so the table shows the same rolls for some repeats.
Doors, windows and the walls underneath
Subtracting doors and windows is optional, and many hangers leave small openings in the count anyway. The short pieces cut above and below an opening are often too short to reuse. In a small room, though, subtracting a door can drop a whole roll.
Paper shows every bump and seam, so the walls need to be smooth and dry first. For bare walls, work out the sheets with the drywall sheet count and the joint compound for the seams.
Mistakes to avoid
- Ordering from the floor area. A square-foot figure cannot show the whole strips and rolls the walls need.
- Leaving out the pattern repeat. The strips will not line up, and the count comes out low.
- Skipping the check on a tall wall. If a strip would be longer than a roll, the calculator shows a message instead of a count.
Common questions
How do you work out how much wallpaper you need?
Find the wall run, divide it by the roll width to get the strips, and see how many strips fit on a roll. The calculator does these steps for you once you enter the room size, the wall height and the repeat.
How much extra wallpaper should I order?
The calculator adds no waste allowance, because it already rounds up to whole strips and rolls. Many hangers still keep a spare roll from the same print run for repairs.
How do I measure a wall?
Measure from the floor to the ceiling at a few spots, and use the tallest reading. Measure the room's length and width wall to wall at the floor, and enter those in the calculator.
How do I calculate the square feet of a room?
Multiply the length by the width for the floor area. The wall area is the wall run times the wall height, but the rolls to buy depend on whole strips, so the calculator counts rolls.
How many rolls of wallpaper do I need for one accent wall?
Measure the width of the wall and divide it by the roll width, which is 20.5 in for a common US double roll. Round up to get the strips. Then see how many strips of your wall height plus the pattern repeat fit on a roll that is 33 ft long, and divide the strips by that, rounding up.
How do I figure out how much peel and stick wallpaper I need?
Many peel and stick rolls are 20.5 in wide and 16.5 ft long. That's about half the length of a 33 ft pasted-paper double roll. Use the same strip method with the size on your label, and confirm with the maker before you order.