Wallpaper calculator

How to use the wallpaper calculator

1. Choose Room to enter the length and width of a rectangular room, or Walls to enter the total width of the walls you will paper, such as a single feature wall.
2. Enter the wall height from floor to ceiling. If the ceiling is not level, use the highest point.
3. Enter how many doors and windows there are, or 0 if the walls you are papering have none. Their sizes, the trim allowance and the seam overlap are under Trim, overlap and opening sizes.
4. Keep the standard 10.05 m × 53 cm roll, or pick Other size and type the width and length from the label. Then choose the pattern match and enter the repeat printed on the label.
5. Read the rolls to buy. Lengths to hang, lengths per roll and paper per length show how the number was reached.

How do you work out how many rolls of wallpaper you need?

Count lengths, not square metres. Wallpaper goes up in vertical lengths, so the number of lengths across the walls is their total width divided by the roll width, rounded up. Each length is the wall height plus a trim allowance; A.S. Création advises adding about 5 cm to the room height to avoid a tight cut.

A pattern adds waste. With a straight match every length starts at the same point of the design, so each length is rounded up to whole repeats. With an offset match such as a half drop, each length starts part of a repeat lower than the one beside it, so when you cut lengths one after another the paper per length is rounded up to end on that offset. Divide the roll length by the paper per length and round down to get whole lengths per roll, then divide the lengths you need by that number and round up.

Doors and windows count only when they replace a whole length. Their area is divided by the area of one full-height length and rounded down, because the short pieces above a door and below a window still have to be cut and matched.

The calculator counts the walls as one continuous run, so it assumes the piece left over at the end of one wall starts the next. If you cannot reuse it, for example in a room of many short walls, add one length for each wall.

How many lengths do you get from a roll of wallpaper?

A standard 10.05 m roll gives 4 lengths of plain paper for walls up to about 2.46 m high and 3 lengths up to 3.30 m, with 5 cm of trim. A pattern repeat can cost a length per roll even on 2.4 m walls.

Computed with the formulas above. The 10.05 m length is the usual roll size given by Boråstapeter and A.S. Création; the 64 cm half drop is the 64/32 cm offset match that Graham & Brown uses as its example.

How many rolls of wallpaper for a room?

A 4 × 3 m room with 2.4 m walls needs 7 standard rolls of plain paper, and the same room with 2.7 m walls needs 9. Every figure below assumes 10.05 m × 53 cm rolls, 5 cm of trim, one 90 × 200 cm door, one 120 × 120 cm window and no pattern repeat.

Above about 2.46 m a 10.05 m roll gives 3 lengths instead of 4, which is why 2.7 m and 3.0 m walls need the same number of rolls. The door and window sizes are examples, not standard sizes; change them to match your room.

Worked examples

Should you take off doors and windows when measuring for wallpaper?

Take them off only where they replace whole lengths. Graham & Brown tells you to ignore doors and windows so that you order a little extra, A.S. Création says to allow for them with spare rolls, and Farrow & Ball asks you to note areas such as doorways that do not need paper. Counting whole lengths sits between these: on 2.4 m walls, a 90 × 200 cm door and a 120 × 120 cm window save 2 lengths, about 2.5 m² of paper, rather than the full 3.24 m² they measure.

Whichever way you count, buy the spare roll at the same time as the rest. Farrow & Ball notes that pattern and colour can differ slightly between batches, so check that every roll carries the same batch number before you cut the first length.