How the wallpaper calculator works
Wallpaper goes up in vertical strips that run from ceiling to floor. The calculator works out how many strips go round the room, how many full strips you get from one roll, and divides.
Strips = room perimeter (in) ÷ roll width, rounded up, minus strips over doors
Strip length = wall height + pattern repeat + 4 in for trimming
Strips per roll = roll length ÷ strip length, rounded down
Rolls = strips ÷ strips per roll, rounded up
Worked example
A 14 by 12 foot room with 8 foot walls has a 52 foot perimeter (624 in). With 20.5 inch rolls that is 31 strips, minus 1 over the door: 30 strips. Each strip is 96 + 0 + 4 = 100 inches, so a 33 foot (396 in) roll gives 3 strips. 30 ÷ 3 = 10 rolls.
Wall area alone (416 sq ft ÷ 56) would suggest 8 rolls, which would leave you short. The leftover 96 inches on each roll is too short for another full strip.
Common roll sizes
| Roll type | Typical size | Coverage |
|---|---|---|
| US double roll | 20.5 in × 33 ft | About 56 sq ft |
| European roll | About 21 in × 33 ft (0.53 × 10 m) | About 57 sq ft |
| Wide or commercial | 27 in or wider | Check the label |
Before you buy
- Check every roll has the same batch or lot number.
- Large repeats (over 18 in) waste more paper; tall walls make it worse.
- Prepasted paper only needs water; unpasted paper needs paste suited to the paper type.
Common questions
How many square feet does a roll of wallpaper cover?
A US double roll is usually 20.5 inches wide and 33 feet long, about 56 sq ft. A European roll is about 21 inches by 33 feet, roughly 57 sq ft. You can use less than that because of trimming and pattern matching.
Why can't I just divide wall area by roll area?
Wallpaper is hung in full-height strips, and each strip has to line up with the pattern. The leftover piece at the end of each roll is usually too short to use, so dividing area by area often leaves you short.
What is a pattern repeat?
The distance before the design repeats down the roll, printed on the label. Each strip may need up to one extra repeat so the pattern matches the strip beside it.
How many extra rolls should I buy?
Buy at least one extra roll from the same batch number. Rolls from a different batch can be a slightly different shade.