Wallpaper calculator — how many rolls do I need?
We calculate in drops, not square metres, and account for the pattern repeat. That is the only correct approach: a roll yields a whole number of drops, and any remainder shorter than the wall is waste.
Why square metres mislead
A standard 0.53 × 10.05 m roll contains 5.3 m². It looks as though two rolls would cover a 4 × 2.7 m wall (10.8 m²). They will not.
- One drop needs 2.7 m + 10 cm for trimming = 2.8 m
- A 10.05 m roll yields 3 drops (3 × 2.8 = 8.4 m); 1.65 m is waste
- You really use 3 × 0.53 × 2.7 = 4.3 m² per roll, not 5.3 m²
- A 4 m wide wall needs 4 ÷ 0.53 = 7.5 → 8 drops
- 8 drops ÷ 3 per roll = 2.67 → 3 rolls
The difference between "two rolls" and "three rolls" is a job at a standstill, because a roll bought later may come from a different batch and differ in shade.
Pattern repeat — the most commonly ignored figure
The repeat is the distance after which the pattern starts again. For neighbouring drops to line up, each drop must be a whole multiple of the repeat — and that can cost you an entire roll. Example: a wall 2.4 m high, a 10.05 m roll.
- No repeat: a drop is 2.5 m and a roll yields 4 drops.
- Repeat of 64 cm: the drop must be 2.56 m (4 × 64 cm) and the same roll yields only 3 drops.
Six centimetres of difference costs you one drop per roll — for a 4 m wide wall that means buying 3 rolls instead of 2. Copy the repeat from the label rather than guessing it.
Practical notes
- Buy from one batch. The batch number is on the roll; different batches can differ in shade, which shows most on plain designs.
- Usually do not subtract openings. The strip above a window still comes off a full-length drop, so the saving is illusory.
- Start from the most visible corner. The last drop is rarely a full one — let the mismatch fall behind a door or a wardrobe.
- Match the paste to the paper. Non-woven, vinyl and paper need different adhesives and different technique — non-woven is pasted onto the wall.
Not sure how the wallpaper will look in the room? Decoria.Studio scans the room with your phone and generates a render of your interior in the style you pick — then builds a shopping list with quantities and prices.
Questions and answers
Why is wallpaper measured in drops rather than square metres?
Because a roll yields a whole number of drops, and any remainder shorter than the wall height is waste. A 0.53 × 10.05 m roll contains 5.3 m², but against a 2.7 m wall you only get 3 drops out of it, so you really use 4.3 m². Calculate in square metres and you will run short.
What is the pattern repeat?
It is the distance after which the pattern repeats, printed on the roll in centimetres. For the pattern to line up between drops, each drop has to be a whole multiple of the repeat — which is why patterned wallpaper needs more rolls than plain.
How many rolls of wallpaper for a 4 × 5 m room?
With 2.7 m walls, 0.53 × 10.05 m rolls and a free-match pattern, 12 rolls for all four walls. For a single feature wall 4 m wide, 3 rolls are enough.
Should I subtract windows and doors?
Usually not. The strips above and below a window still have to be cut from a full-length drop, so the saving is illusory. Only subtract genuinely large areas, such as a full-wall patio door, and reduce the width to be covered by its width.
How much spare wallpaper should I allow?
The calculator already adds 10 cm for trimming the top and bottom of each drop, and rounding up to whole rolls adds more. With a large pattern repeat, or if this is your first time hanging wallpaper, buy one spare roll from the same batch.