Wallpaper Calculator
Calculate how many wallpaper rolls you need for any room, accounting for doors and windows.
By Syed Mubashir Ali · Last updated
Pattern repeat: the hidden cost
The repeat is the vertical distance before the pattern starts over, printed on the roll label. A 64cm repeat on a 2.4m wall means each drop wastes up to 64cm aligning the pattern: nearly a quarter of the roll. Large repeats on short walls are the most expensive combination in wallpapering.
Plain and small-pattern papers have effectively no repeat waste, which is why they need fewer rolls for the same wall. When comparing prices between designs, factor the repeat in: the cheaper roll with the big repeat often costs more in total.
DIY or hire someone
A competent DIYer can paper a plain rectangular room in a day. The jobs worth paying for are stairwells (long drops, awkward access), large-pattern papers (matching across walls takes practice), and anything above a staircase where a fall hurts. A decorator charges roughly a day rate per average room.
If you DIY, the two things that actually matter are a sharp blade (change it often: a blunt blade tears) and keeping the first drop plumb. Every subsequent drop follows the first, so an error there compounds across the wall.
How to Use Wallpaper Calculator
- 1Choose metres or feet, then enter the room dimensions and wall height.
- 2Enter the number of doors and windows so their areas can be deducted.
- 3Optionally add a price per roll for a cost estimate.
- 4Press Calculate.
- 5You get the number of rolls needed and the cost if priced. Buy the rolls in one order so they come from the same batch.
- 6Measure each wall separately rather than using the room perimeter. Walls differ: chimney breasts, alcoves and sloping ceilings all change the drop count, and a single room figure hides that.
- 7Order all rolls together and check the batch numbers match on delivery. One extra roll from the same batch, kept unopened, is the cheapest insurance you will ever buy.
Frequently Asked Questions
Why does batch number matter?
Because wallpaper colour varies subtly between print batches, and two rolls from different batches hung on the same wall show a visible join in daylight. Order everything at once, check the batch numbers match on delivery, and keep a spare roll.
Does it account for pattern repeat?
No, and this is the main thing to add yourself. A large repeat can waste a substantial part of every drop, because each length must start at the right point in the pattern. A 64cm repeat on a 2.4m wall can cost you an extra roll or two: check the repeat on the roll label and allow accordingly.
Should I really deduct doors and windows?
Deduct them, but do not be too precise about it. A standard door is worth deducting; a small window often is not, because you still need full drops either side of it and the offcuts rarely reach anywhere useful.
How many rolls should I have spare?
One, from the same batch. Wallpaper is discontinued and rebatched constantly, and a single damaged drop two years later is a whole-wall problem if you cannot match it.
Does it work for feature walls?
Enter the dimensions of that wall alone rather than the room. The calculation is the same; you are just giving it a smaller area.
What is a drop?
One vertical length of wallpaper from ceiling (or coving) to skirting, cut a few centimetres long at each end for trimming. A standard roll (53cm x 10m) yields three to four drops on a normal 2.4m ceiling: the calculator works this out from your wall height.
Paste-the-wall or paste-the-paper?
Paste-the-wall (non-woven) is easier: you paste the wall and hang dry paper, no soaking table, no waiting. Traditional paste-the-paper needs booking time for the paste to activate. If you are doing it yourself for the first time, paste-the-wall is the forgiving choice.
How do I go around sockets and switches?
Turn the power off, hang the drop over the socket, then cut diagonally from the centre outward and trim around the faceplate. The plate covers the cut edges. Do not try to cut a neat hole in advance: it never lands where you expect.
About Wallpaper Calculator
The Wallpaper Calculator estimates how many rolls a room needs from its dimensions and height, deducting for doors and windows, with an optional cost. It runs entirely in your browser.
The figure it gives assumes a plain or free-match paper. The one adjustment you should make yourself is for pattern repeat: papers with a large repeat waste part of every drop, because each length has to begin at the right point in the design, and a long repeat on a standard ceiling height can add a roll or two to the order.
Order everything in one go and check the batch numbers match. Print batches differ in colour by enough to show as a line down a wall in daylight, and it is not something you can correct after hanging.
Keep a spare roll from the same batch. Papers are discontinued and rebatched often, and without a spare a single damaged drop becomes a redecorated wall.
Wallpaper is unforgiving of shortfalls in a way paint is not. A tin of paint can be re-bought and matched; a discontinued wallpaper cannot. That is why every part of this calculation leans toward having a little too much: the spare roll in the loft is worth more than the money it cost.