Wallpaper Calculator
Find how many wallpaper rolls you need for a room using the strip method that installers use, with pattern repeat, doors, windows, roll size presets and cost. Example: a 12 by 14 foot room with 8 foot walls needs 10 double rolls of standard 20.5 inch wallpaper.
Show steps
How to use the Wallpaper Calculator
- Choose feet or meters and enter the room length, width and wall height.
- Enter the number of doors and windows and pick your roll size (or enter a custom size).
- Add the pattern repeat from the roll label, if there is one.
- Press Calculate to see the strips, rolls and cost.
Formula and method
Strip method: strip length = wall height + trim, rounded up to the pattern repeat. Strips per roll = floor(roll length / strip length). Strips needed = (room perimeter – door widths) / roll width, rounded up. Rolls = strips / strips per roll, rounded up. Area method: net wall area x (1 + waste) / roll area.
Worked example: 12 x 14 ft room, 8 ft walls, 1 door, 2 windows
| Step | Result |
|---|---|
| Perimeter 2 x (12 + 14) | 52 ft |
| Strip length (8 ft + 4 in) | 8.33 ft |
| Strips per 33 ft roll (33 / 8.33) | 3 |
| Strips needed ((52 – 3) / 1.708) | 29 |
| Rolls (29 / 3, rounded up) | 10 |
Wallpaper roll sizes
| Roll | Width | Length | Area |
|---|---|---|---|
| US double roll | 20.5 in | 33 ft | 56 sq ft |
| US single roll | 20.5 in | 16.5 ft | 28 sq ft |
| European roll | 21 in (53 cm) | 33 ft (10.05 m) | 58 sq ft |
| European wide roll | 27.5 in (70 cm) | 33 ft (10.05 m) | 76 sq ft |
How pattern repeat changes the amount
A drop-match or straight-match pattern repeats every so many inches. Each strip must be cut so the pattern lines up with the next one, so a bigger repeat wastes more paper at the top of each strip. Add the repeat length to the calculator to see the exact effect.
Tips for ordering
Measure the walls you will actually paper. Buy one extra roll from the same print run for repairs, check the batch number, and unroll rolls to confirm the pattern before hanging.
Frequently asked questions
How do I calculate how many rolls of wallpaper I need?
Divide the room perimeter by the roll width to get strips, work out how many strips each roll yields from the wall height, then divide.
What is pattern repeat?
The vertical distance before a wallpaper pattern repeats. A larger repeat means more waste.
How much extra wallpaper should I buy?
About 10% extra, or one spare roll, for mistakes and future repairs.
What is the difference between a single and double roll?
A double roll is twice as long as a single roll, about 56 sq ft versus 28 sq ft in the US.
Should I subtract doors and windows?
Subtract full-height doors from the strips, and be cautious about windows because the strips above and below still need paper.
Does a ceiling need wallpaper too?
Treat it as a separate surface and measure its area.
Sources
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