How to use the wallpaper calculator
- Enter the length and width of the room and the wall height. To paper only some walls, enter half of their total width as the length and 0 as the width.
- Enter the roll width and length from the label. A common US double roll is 20.5 in × 33 ft. A standard European roll is 53 cm × 10.05 m.
- Enter the pattern repeat printed on the label, or 0 for plain and random-match papers.
The strip method
Wallpaper is hung in vertical strips, and offcuts are usually too short to reuse. That is why this calculator counts whole strips rather than dividing the wall area by the roll area.
Strips needed = room perimeter ÷ roll width (rounded up) Strip length = wall height + trimming allowance (4 in / 10 cm), rounded up to a whole number of pattern repeats Strips per roll = roll length ÷ strip length (rounded down) Rolls = strips needed ÷ strips per roll (rounded up)Common roll sizes
| Roll | Size | Coverage |
|---|---|---|
| US double roll | 20.5 in × 33 ft | about 56 sq ft |
| Standard European roll | 53 cm × 10.05 m | about 5.3 m² |
| Wide European roll | 70 cm × 10.05 m | about 7 m² |
In the US, wallpaper is often priced per single roll but sold only in double rolls. This calculator counts the rolls you enter, so a 33 ft roll is counted as one double roll.
Worked example
A 12 × 14 ft room with 8 ft walls and 20.5 in × 33 ft double rolls, no pattern repeat:
- Perimeter: 2 × (12 + 14) = 52 ft = 624 in. 624 ÷ 20.5 = 30.4, so 31 strips.
- Strip length: 96 in + 4 in = 100 in. 396 in ÷ 100 in = 3.96, so 3 full strips per roll.
- Rolls: 31 ÷ 3 = 10.3, so 11 double rolls.
Tips
- Large pattern repeats waste more paper per strip, so check the result after entering the repeat.
- Keep one spare roll for future repairs, since the same batch can be hard to find later.
- For painting instead, use the paint calculator.
Frequently asked questions
How many rolls of wallpaper do I need for a 12 × 12 room?
With 8 ft walls and 20.5 in × 33 ft double rolls, a 12 × 12 ft room needs 29 strips at 3 strips per roll, so about 10 double rolls.
What is a pattern repeat?
It is the vertical distance before the design repeats. Each strip must start at the same point in the pattern, so longer repeats mean more waste.
Should I subtract doors and windows?
Most installers don't subtract small openings. The paper around them is still needed for matching, and the extra covers mistakes.
What is the difference between a single and a double roll?
In the US, a double roll is twice the length of a single roll, about 33 ft instead of 16.5 ft. Prices are often quoted per single roll even though only double rolls are sold.