Wallpaper Calculator
Work out how many wallpaper rolls a room needs — strips from the perimeter, strip length with the pattern repeat, and rolls to buy.
Wallpaper is not estimated by area — it is estimated by strips. Each strip runs floor to ceiling, each must match the pattern, and each comes off a roll of fixed length. This calculator follows the professional strip method.
Openings are deliberately not deducted: the offcut above a door is rarely reusable, and running short mid-wall is worse than a spare roll.
Your results
Enter your measurements and press Calculate.
Quantities are rounded up to whole tiles, planks, boxes or bags, after the wastage allowance. Cost appears only when you enter a price.
Formula
All lengths are converted to a single unit before the calculation: 1 ft = 0.3048 m, 1 in = 25.4 mm, 1 ft² = 0.09290304 m², 1 yd² = 9 ft². Material quantities are rounded up — you cannot buy part of a tile, plank or bag.
How to use this calculator
- Measure the room length, width and wall height.
- Enter the roll width and length from the packaging.
- Enter the pattern repeat (0 for plain paper).
- Read the strips and rolls — buy the rolls shown, plus one spare for future repairs.
Worked example
| Room | 12 ft × 15 ft × 8 ft high |
|---|---|
| Perimeter | 2 × (12 + 15) = 54 ft = 648 in |
| Strips (20.5 in roll) | ⌈648 ÷ 20.5⌉ = 32 strips |
| Strip length (12 in repeat) | 8 ft + 1 ft = 9 ft |
| Rolls (33 ft roll) | ⌈(32 × 9) ÷ 33⌉ = ⌈8.73⌉ = 9 rolls |
Check it by hand: every step above uses the formula in the box. If your numbers match the example inputs but the calculator gives a different answer, please report it via the contact page.
Frequently asked questions
What is pattern repeat?
The vertical distance after which the pattern starts again — printed on the roll (e.g. 305 mm / 12 in). Each strip must be cut longer by one repeat so the pattern lines up at the joins. Plain paper has a repeat of 0.
Why are doors and windows not deducted?
Because wallpaper is cut in full strips and matched at the pattern: the piece cut out for a door or window is usually too short or wrongly matched to use elsewhere. Professionals estimate on the full perimeter, and this calculator does the same.
How many rolls should I buy?
The number shown, plus one spare roll from the same batch for future repairs. Wallpaper batches (dye lots) can differ in shade — a later roll may not match.
What is the difference between a single roll and a double roll?
A US double roll is twice the length of a single roll (about 66 ft vs 33 ft) at the same width. European rolls are usually sold as single rolls of 10 m. Always check whether the price is per single or double roll.
Related calculators
Estimates only. Results are for planning. Measure twice, confirm box coverage and tile sizes on the packaging you buy, and follow the manufacturer's instructions. See the disclaimer.