Wallpaper calculator

How it works

Formula: Rolls = strips needed ÷ whole strips per roll

Wallpaper goes up in vertical strips (drops). A strip is the wall height plus the pattern repeat and a trim margin. A roll only gives whole strips: 33 ft ÷ 8.33 ft = 3 strips, and the rest is lost. The number of strips is the width of the walls (perimeter minus doors and windows) divided by the roll width. Divide the strips by the strips per roll and round up to a whole roll.

Worked examples

• A 12 × 10 ft room, 8 ft walls, rolls of 20.5 in × 33 ft

  23 strips, 3 per roll: 8 rolls.

• 9 ft walls with a 25 in pattern repeat

  Only 2 strips per roll: 12 rolls.

• The same room with 27 in wide rolls

  6 rolls.

Common mistakes

• Dividing the wall area by the area of a roll: 6 rolls.

  A roll only gives whole strips: you need 8.

• Forgetting the pattern repeat.

  With a 25 in repeat on 9 ft walls, each roll gives only 2 strips: 12 rolls.

• Buying rolls from different batches.

  The shade can vary from one batch to another: buy every roll with the same batch number.

What the calculation leaves out

• Straight walls of the same height. Openings are taken off over their full width: above doors and below windows, offcuts are often enough.
• The roll size and the repeat are printed on the label: the tool does not guess them.

Rolls of 20.5 in × 33 ft for a room perimeter of 44 ft

Frequently asked questions