How many wallpaper rolls

How it works

We estimate the wall surface and divide it by the surface of one roll, adding about 15% for trimming and pattern matching.

Note

Large-pattern designs need more material to match the print: allow a bigger margin.

The pattern repeat is the number that decides everything

On the roll label, next to the dimensions, there is a figure almost nobody looks at: the repeat, that is how many centimetres apart the motif comes round again vertically. That is what decides the waste, not the surface area. With a repeat of 64 centimetres, every drop has to be cut to the next multiple of 64 above the wall height, and whatever is left at the bottom is thrown away.

On a wall 260 high with a 64 repeat you need five repetitions, that is 320 centimetres of paper to cover 260: twenty per cent goes before you even start. It is why a fifteen per cent margin is enough on plain colours and almost never enough on a large pattern.

Straight match and offset match

If the pattern lines up at the same height on every drop, the match is straight and the calculation is the one above. If instead it is offset, that is every drop has to be shifted by half a repeat against the previous one, the waste nearly doubles because two consecutive drops never start from the same point. On the label the difference is shown with two symbols, two arrows side by side or staggered.

There is however a compensation paper hangers always use: with an offset match, the offcut of one drop often serves to start the next. It is worth numbering the drops and keeping the offcuts until the wall is finished.

Count drops, not square metres

Wallpaper is not hung by area, it is hung in whole vertical strips: nobody cuts a drop in half lengthwise, except the last one in a corner. The honest calculation is therefore how many drops fit across the width of the wall, rounded up, and how many drops come out of a roll, rounded down.

From which follows a practical consequence: doors and windows do not reduce the number of rolls as much as their area suggests, because the strip crossing them has to be bought whole anyway. Above a door you need a piece, below a window another, and both must have the pattern aligned with the drops beside them.

The batch, and the wall underneath

As with tiles, the label carries a print run number: two runs of the same design can differ by a shade, and in one room it shows. Buy it all at once, with a spare roll.

And there is one thing no calculation saves you from: wallpaper does not hide defects, it reveals them. A wall with cracks, waves or badly stripped old paper gives every imperfection back under raking light, and smooth, glossy papers most of all. Preparation, with skimming and sizing, is the part of the job that decides the result.

Nearby tools

The wall dimensions come from Room area and volume. For the plain-colour alternative there is How much paint you need, for the floor How many tiles you need and for the light in the room How many lumens you need.