How to Measure for Wallpaper

Step 1: measure the width of each wall

Measure each wall to be papered along the middle of the wall, at the widest point, and add the widths together. Include the width of the door and window openings, because paper around them still has to be matched and cut, and the offcuts are rarely reusable.

Write down each measurement with its unit. If you are papering a chimney breast or a single feature wall, measure just that wall and treat it as its own job.

Step 2: measure the height

Measure from the top of the skirting board to the ceiling or picture rail, at three points along each wall, and use the tallest figure. Ceilings and floors are rarely perfectly level, and the tallest figure keeps you from running short.

Add 10 cm to the height for trimming at the top and bottom. This is the length each drop needs before the pattern is taken into account.

Step 3: read the roll label

The label tells you the roll width and length, the pattern repeat, the type of match and the batch number. Many UK rolls are around 52–53 cm wide and 10 m long, but check the label, because some rolls are wider or shorter.

A plain or free-match paper has no repeat. A straight match has the pattern at the same height on every drop, and an offset (half-drop) match shifts the pattern on alternate drops, which can use more paper. Buy all rolls from the same batch where you can, because colour can vary slightly between batches.

Step 4: count the drops and the rolls

Divide the total wall width by the roll width and round up to a whole number: that is the number of drops. Take the height with trimming added, and round it up to the next pattern repeat to get the cut length of each drop. Then divide the roll length by the cut length and round down to see how many drops one roll gives.

Divide the number of drops by the drops per roll and round up. Finally, add an allowance of about 10% for mistakes and damaged lengths. The wallpaper calculator does all of this for you and shows the working.

• 12 m of wall ÷ 52 cm = 23.1, so 24 drops.
• 240 cm + 10 cm trim = 250 cm, rounded up to five 53 cm repeats: 265 cm per drop.
• A 10 m roll ÷ 265 cm = 3 drops per roll.
• 24 drops ÷ 3 = 8 rolls, and 10% extra adds 3 spare drops: 9 rolls.

Awkward areas and what to check

Sloping ceilings, bay windows and stairwells need extra length, so measure the longest drop and add a little more. For a very large window or a wide opening, you may be able to deduct it, but be cautious, because the offcut will not always be reusable.

Keep one unopened spare roll until the work is finished and check the retailer's returns policy before you open any rolls. Check the batch numbers match before you start hanging, because it is hard to fix a mismatch once the paper is on the wall.