Wallpaper Quantity Calculator

The shop's chart asks for the perimeter and gives a number, which is fine until the paper has a pattern. A repeat means every drop must start at the same point in the design, so a bit comes off the top of most of them — and that is why people come back for one more roll, from a different batch, which never quite matches.

Perimeter of the room, in metres

Add up the walls you are papering.

Wall height, in metres

Floor to ceiling, or to the picture rail.

Roll length, in metres

A standard European roll is 10.05.

Roll width, in metres

Usually 0.53; American rolls are wider.

Pattern match

Pattern repeat, in centimetres

On the roll label. Ignored for a free match.

Doors and windows, in square metres

Taken off the area, not off the drops.

Spare rolls

For mistakes and future repairs. Buy them in the same batch.

12 rolls

11 to paper the room, plus 1 spare. 31 drops of 2.56m, 3 from each roll, with 2.37m left on every roll.

✓ The rolls yield at least the drops you need — 11 rolls give 33 drops, and the walls take 31
✓ Each drop is cut to a whole number of repeats — 2.56m cut for a 2.4m wall, which is 8 repeats of 32cm
✓ The drops cover the walls right round — 31 drops at 0.53m wide covers 16.43m of a 16m perimeter
✓ The offcut per roll is what the arithmetic leaves — 2.37m left on each roll — less than one drop, or another drop would fit
✓ Spares are added on top rather than counted as coverage — 11 to do the job plus 1 spare — buy them together, since batches differ

What this generator does

Counts the drops the perimeter needs, lengthens each drop to a whole number of pattern repeats, works out how many fit on a roll, and reports what is left over.

How to use this tool

Add up the walls you are papering and type the perimeter.
Type the wall height, and the roll size off the label.
Say what the pattern match is and how long the repeat is.
Read how many rolls, and how many drops come off each one.

Understanding the controls

Perimeter of the room: The total length of the walls you are papering, in metres. Leave out a wall you are not doing.
Wall height: Floor to ceiling, or as far up as the paper goes. This sets how long each drop has to be before any pattern allowance.
Roll length: Off the label. A standard European roll is 10.05 metres; American rolls differ.
Roll width: Off the label, usually 0.53 metres. This decides how many drops it takes to go round the room.
Pattern match: Free match papers can be cut anywhere. A straight match lines the pattern up across the drops, and an offset match drops every other length by half a repeat.
Pattern repeat: How far apart the design repeats, in centimetres, from the label. Each drop is cut to a whole number of these, which is where the waste comes from.
Doors and windows: Taken off the area covered, but not off the drops — you still hang a full drop over a door and cut round it.
Spare rolls: Added on top of what the job needs. Buy them at the same time: rolls from another batch are printed slightly differently.

Common use cases

Buying wallpaper for a room with a large pattern repeat
Checking a shop's figure before paying for it
Working out whether a feature wall takes two rolls or three
Seeing how much a big repeat costs you in waste
Deciding how many spare rolls to buy from the same batch

How this generator works

The perimeter divided by the roll width gives the number of drops, rounded up. Each drop is then cut to a whole number of pattern repeats, so a 2.4 metre wall with a 32 centimetre repeat takes a 2.56 metre drop. How many of those come off a roll is a whole number too, and what is left is genuinely waste. The checks work back the other way: the rolls bought must yield at least the drops needed, each drop must be a whole number of repeats, the drops must cover the perimeter, and the offcut on each roll must be less than one drop — because if it were more, another drop would fit.

Randomness and fairness

Nothing is random. The same room and the same paper always give the same answer.

For how randomness is produced across the whole site, see how Generate Random works.

Limitations and good to know

Doors and windows are taken off the area but not off the drops, which is how decorators price it — you cut round them rather than skipping a drop.
Sloped ceilings, dormers and stairwells need drops of different lengths and are not covered.
An offset match wastes more in practice than the arithmetic shows, because the half-repeat offcuts are rarely usable elsewhere.
Roll sizes vary by manufacturer; take them from the label rather than the defaults.

Privacy and your data

Room sizes and roll dimensions are used only for the arithmetic on this page, in your browser. Nothing about your room is uploaded or kept.