How many rolls of wallpaper do I need?
Measure the length and width of the room and the wall height, and count the doors and windows: the calculator takes off 20 sq ft for each, as Sherwin-Williams does. Read the roll size and pattern repeat from the label; a standard double roll is 20.5 in × 33 ft, about 56 sq ft.
A roll covers less than its size because it's cut into full-height strips. York says to add about 4 in to each strip for trimming at the ceiling and baseboard, and each strip is rounded up to whole pattern repeats. What's left at the end of the roll is too short for another strip.
Source Sherwin-Williams · How-To Estimate How Much Wallpaper You Need ↗York Wallcoverings · Installation guide (trimming allowance) ↗York Wallcoverings · Interlock wallpaper (double roll size and repeat) ↗
How to calculate wallpaper
Here it is with your numbers:
- Add up the four walls and multiply by the height: (12 + 15 + 12 + 15) × 8 = 432 sq ft.
- Take off 20 sq ft for each door and window: 432 − (3 × 20) = 372 sq ft.
- Each strip is the wall height plus 4 in for trimming: 96 + 4 = 100 in.
- Round up to whole 15 in pattern repeats: 7 × 15 = 105 in.
- Strips from one 396 in roll: 396 ÷ 105 = 3.7714, so 3 full strips.
- One roll covers strips × roll width × height: 3 × 20.5 × 96 ÷ 144 = 41 sq ft.
- Divide the area by what one roll covers: 372 ÷ 41 = 9.0732, rounded up to 10 rolls.
It means buying 10 rolls of 20.5 in × 33 ft wallpaper, all with the same run number.
The answer starts with Sherwin-Williams' own example room, which their table puts at 10 double rolls. Buy every roll with the same run number: colors can differ slightly between print runs.
Wallpaper for common room sizes
Walls 8 ft high, with 1 door and 2 windows, plain paper (no repeat) on 20.5 in × 33 ft rolls.
| Room | Area to cover | Rolls |
|---|---|---|
| 10 × 10 ft | 260 sq ft | 7 |
| 12 × 10 ft | 292 sq ft | 8 |
| 12 × 12 ft | 324 sq ft | 8 |
| 14 × 12 ft | 356 sq ft | 9 |
| 16 × 12 ft | 388 sq ft | 10 |
| 16 × 14 ft | 420 sq ft | 11 |
| 20 × 16 ft | 516 sq ft | 13 |
FAQs
How do I calculate how much wallpaper I need?
Add up the walls and multiply by the height, take off 20 sq ft for each door and window, then divide by what one roll covers once it's cut into strips. Sherwin-Williams' 12 × 15 ft room with 8 ft walls has 372 sq ft to cover: 10 double rolls with a 15 in repeat.
Source Sherwin-Williams · How-To Estimate How Much Wallpaper You Need ↗
How many wallpaper rolls for a 10x10 room?
With 8 ft walls, 1 door and 1 window, a 10 × 10 ft room has 280 sq ft to cover. Rolls of 20.5 in × 33 ft give 3 strips each, so 7 rolls for plain paper. A large pattern repeat can need more.
How much wallpaper do I need for a 10x12 room?
With 8 ft walls, 1 door and 1 window: 312 sq ft, or 8 rolls of 20.5 in × 33 ft plain paper.
How much wallpaper for a 12x12 room?
With 8 ft walls, 1 door and 1 window: 344 sq ft, or 9 rolls of 20.5 in × 33 ft plain paper.
Is one roll of wallpaper enough for one wall?
Only for a narrow wall. A 20.5 in × 33 ft roll gives 3 strips for an 8 ft wall, which covers about 5 ft of wall. A 10 ft wide wall takes 2 rolls.
Source York Wallcoverings · Interlock wallpaper (double roll size and repeat) ↗
What does pattern repeat mean on wallpaper?
It's how far down the paper the design takes to repeat. Each strip has to start at the same point in the design, so strips are cut to whole repeats and a big repeat wastes more paper. Graham & Brown: in a straight match the pattern lines up straight across the edges; in an offset (drop) match it lines up at a set distance down.
Source Graham & Brown · How to measure for wallpaper (match types) ↗
Sources
- Sherwin-Williams: How-To Estimate How Much Wallpaper You Need
- York Wallcoverings: Installation guide (trimming allowance)
- York Wallcoverings: Interlock wallpaper (double roll size and repeat)
- Graham & Brown: How to measure for wallpaper (match types)