How the wallpaper calculator works
Most wallpaper calculators only divide the wall area by the area of a roll, which gives the wrong answer when your wallpaper has a pattern. Wallpaper is hung in strips, and each strip has to be cut from the roll in one piece. This calculator works out the number of strips for your wall, how many strips fit on each roll, and then the number of rolls, including the paper lost to a pattern repeat.
Choose One wall for an accent wall, or Whole room to enter the room size and the number of doors and windows.
Common wallpaper roll sizes
| Roll | Width × length | Notes |
|---|---|---|
| US double roll | 20.5 in × 33 ft | Sold as a double roll, about 56 sq ft |
| European roll | 21 in (53 cm) × 33 ft (10 m) | The most common size in the UK and Europe |
| Wide roll | 27 in × 27 ft | Fewer seams for a large room |
| Peel and stick | 20.5 in × 16.5 ft | Often sold as a single roll |
Always check the width and length printed on the product you are buying. Some brands differ, and the difference can change the number of rolls.
What is a pattern repeat and a match?
The pattern repeat is the distance between one point on the pattern and the next time it appears, measured down the roll. It is printed on the label.
- Random match or no pattern: strips can be hung in any order, so there is almost no waste.
- Straight match: the pattern lines up across the strips at the same height. Each strip must start at the same point in the repeat, so you lose paper at the top of every strip.
- Drop (half drop) match: the pattern lines up diagonally, so every second strip is offset by half the repeat. It loses the most paper.
The larger the repeat, the more paper you lose. The calculator accounts for the repeat in the strips per roll, so the answer changes as you change it.
How many rolls do you need?
- Measure the width of the wall, or the room perimeter (twice the length plus twice the width).
- Divide by the roll width to get the number of strips, and round up.
- Measure the wall height and add about 4 in for trimming.
- Divide the roll length by the strip length, rounding down, to find the strips per roll.
- Divide the number of strips by the strips per roll, and round up.
Worked examples
A 10 ft accent wall, 8 ft ceiling
Plain or random-match paper on a US double roll: 6 strips, with 3 strips on each roll, so you need 2 rolls. That leaves no spare strip, so buy a third roll if you can.
A 12 ft × 10 ft room, 8 ft ceiling, one door and two windows
The perimeter is 44 ft, less 3 ft for the door and 3 ft for the windows. That is 23 strips, and 3 strips from each roll, so 8 rolls of a US double roll.
Common mistakes
- Dividing wall area by roll area. This ignores waste from cutting strips and from the pattern repeat, and it leaves you short.
- Forgetting the trim allowance. Each strip needs a few inches at the top and bottom.
- Buying from different batches. Colours vary a little between print runs. Buy all the rolls at once and check that the batch numbers match.
- Not buying a spare roll. A mistake, a repair later or a bad cut is much easier to deal with if you have one.
- Ignoring the match. A drop match can need a whole extra roll over a random match.
Tips for hanging wallpaper
- Start in the least visible corner, so that any mismatch where the last strip meets the first is hardest to see.
- Use a plumb line for the first strip, because corners and ceilings are rarely straight.
- Prime the wall first. It helps the paper stick, and makes it easier to remove later.
- For a statement wall, plan so that the pattern is centred on the focal point, such as a bed or a fireplace.
