Wallpaper Calculator

How wallpaper quantities are worked out

Multiply the room perimeter (all four walls) by the wall height to get the wall area, then divide by the roll coverage. A standard 10m roll covers about 5.2 m². Large pattern repeats waste more paper, so round up generously.

Worked example: a 4 m × 5 m room with 2.4 m ceilings

The perimeter is 18 m, so the wall area is 18 × 2.4 = 43.2 m². Take off roughly 4 m² for a door and a window and you are papering 39 m². A standard UK roll covers about 5.2 m², so that is 8 rolls — buy 9. The spare is not waste: dye lots vary slightly between batches, and a damaged drop three rolls in cannot be matched later.

Pattern repeat changes the maths

A plain or free-match paper wastes almost nothing. A 64 cm straight-match repeat can add 20–25% to the roll count because every drop has to be cut back to the same point in the pattern. This calculator assumes no repeat, so if the label quotes one, add a roll for a room this size.

Preparation is most of the job

Wash the walls with sugar soap, fill and sand any holes, and size bare plaster so the paste grabs evenly. Uneven walls are quicker to fix with lining paper than with filler. Check whether the paper is paste-the-wall, paste-the-paper or pre-pasted before you start mixing anything, and keep a plumb line for the first drop so every subsequent seam lines up.

Tools worth having

A sharp trimming knife with spare blades, a papering brush or smoother, a seam roller, a spirit level for the first drop, and a pasting table if you are pasting the paper. Drop a dust sheet and keep a damp sponge to hand — dried paste on a finished wall is far harder to remove than a wet smear.

Common mistakes

Ordering the exact number of rolls with nothing spare. Ignoring repeat waste on a patterned paper. Papering over damp plaster, which guarantees the seams lift. Mixing two batch numbers in one room. And cutting drops before checking the pattern runs the right way up on every roll.