How the wallpaper calculator works
Wallpaper is hung in vertical strips called drops, so the number of rolls you need depends less on the area of the wall and more on how many full-height drops you can cut from each roll. The calculator works it out in the same way a decorator would:
drops needed = (wall area − doors − windows) ÷ (wall height × roll width), rounded up
cut length per drop = wall height + trim, rounded up to a whole pattern repeat
drops per roll = roll length ÷ cut length, rounded down
rolls = drops needed ÷ drops per roll, rounded up
It assumes the standard UK and European roll, which is 10.05m long and 53cm wide and covers about 5.3m² before any waste. Most wallpaper sold in UK DIY stores uses this size, but some designer and imported papers come in wider or longer rolls, so check the label and change the roll size under "Roll size and trimming" if yours is different.
What is a pattern repeat?
The pattern repeat is the distance before the design starts again down the roll. It's printed on the label, often with a symbol for the type of match:
- Free match (plain, textured or vertical stripes): no repeat, so enter 0. You waste the least paper.
- Straight match: the pattern lines up straight across from one drop to the next.
- Offset or half-drop match: each drop is moved down by half the repeat. Labels show this as something like 53/26, meaning a 53cm repeat with a 26cm offset.
To line up a repeat, you have to cut each drop to a whole number of repeats, so the calculator rounds the cut length up. A bigger repeat means more paper ends up in the bin, which is why a bold floral can need two or three more rolls than a plain paper in the same room.
Worked example: a 4m × 3.5m bedroom
Take a bedroom 4m long and 3.5m wide with 2.4m high walls, one door and one 1.5m² window, papered in a plain design:
- Distance around the room: 2 × (4 + 3.5) = 15m, so the walls are 15 × 2.4 = 36m²
- Take off the door (1.5m²) and window (1.5m²): 33m²
- Each drop covers 2.4 × 0.53 = 1.272m², so 33 ÷ 1.272 = 25.9, rounded up to 26 drops
- Cut length: 2.4m + 10cm for trimming = 2.5m. A 10.05m roll gives 4 drops
- Rolls: 26 ÷ 4 = 6.5, rounded up to 7 rolls
Now swap to a paper with a 53cm pattern repeat. The 2.5m cut has to be rounded up to five repeats, or 2.65m, so each roll only gives 3 drops. You'd need 26 ÷ 3 = 8.7, rounded up to 9 rolls, two more than the plain paper.
Rolls of wallpaper needed for common rooms
Standard 10.05m × 53cm rolls, 2.4m walls, one door and one 1.5m² window:
| Room | Drops | Rolls, no repeat | Rolls, 53cm repeat |
|---|---|---|---|
| Box room, 3m × 2.5m | 19 | 5 | 7 |
| Double bedroom, 4m × 3.5m | 26 | 7 | 9 |
| Living room, 5m × 4m | 32 | 8 | 11 |
| Feature wall, 4m wide, no openings | 8 | 2 | 3 |
Tips before you buy wallpaper
- Buy a spare roll. Rolls are printed in batches and the colour can vary slightly from one batch to the next. Check every roll has the same batch number, and keep one spare for repairs.
- Measure the full width of every wall, including chimney breasts and alcoves. Add the sides of a chimney breast to the room length.
- Use offcuts for short drops above doors, above radiators and below windows. The calculator counts doors and windows as area saved, so it relies on you reusing offcuts in these places.
- Lining paper first? Lining paper is often sold in longer rolls, so work it out separately with its own roll length.
- Ceilings: treat the ceiling as a wall, entering the room width as the length, 0 as the width and the room length as the "height", with doors and windows set to 0.
Painting the other walls? The paint calculator works out litres and tins of emulsion, and the square metre calculator adds up the area of awkward-shaped rooms. If you're tiling a bathroom instead, try the tile calculator.
Frequently asked questions
How many rolls of wallpaper do I need for a 4m × 4m room?
With 2.4m walls, one door and one 1.5m² window, a plain paper needs 28 drops. A standard 10.05m roll gives 4 drops of 2.5m, so you need 7 rolls, or 8 with a spare.
How many square metres does a roll of wallpaper cover?
A standard UK roll is 10.05m × 0.53m, which is 5.3m². In practice you get less because each drop has to be cut to full height plus trimming, so on 2.4m walls you cover about 5m² of wall per roll (4 drops of 2.4m × 0.53m) with plain paper.
How many rolls of wallpaper for a feature wall?
A 4m wide wall 2.4m high needs 8 drops of 53cm paper. With no pattern repeat you get 4 drops a roll, so 2 rolls; with a 53cm repeat you get 3 drops a roll, so 3 rolls.
How much extra wallpaper should I buy for pattern repeat?
It depends on the repeat and your wall height. On 2.4m walls, a 53cm repeat cuts the drops per roll from 4 to 3, so you need roughly a third more rolls than for plain paper.
How many drops do you get from a roll of wallpaper?
With 2.4m walls and 10cm for trimming, a 10.05m roll gives 4 drops of 2.5m. With 2.7m ceilings or a large pattern repeat, you usually only get 3.
Last reviewed October 2026 using 2026/27 figures. This calculator gives an estimate for guidance only.