Square-foot formulas get wallpaper wrong because you cannot use the offcuts. Installers count strips, and so does this.
Wallpaper calculator
Measure the wall width and height. Find the repeat and match on the roll label.
How we count
- Strips = total wall width ÷ roll width, rounded up.
- Drop length = wall height plus 4 inches for trimming, rounded up to the next full pattern repeat. A drop match adds half a repeat.
- Strips per roll = roll length ÷ drop length, rounded down.
- Rolls = strips (plus your extra) ÷ strips per roll, rounded up.
We do not subtract doors and windows: the pieces above and below them rarely use up whole strips. For a very big window wall you can subtract its width.
Roll sizes
| Roll | Size | Coverage |
|---|---|---|
| US double roll | 20.5 in x 33 ft | 56 sq ft |
| European roll | 53 cm x 10 m | about 57 sq ft |
| Wide (American) double roll | 27 in x 27 ft | about 70 sq ft |
US wallpaper is often priced per single roll but sold only in double rolls. Check the label.
Sources
- Magnolia Home wallpaper (York): double roll 20.5 in x 33 ft = 56 sq ft
- Selected Wallpapers: European rolls vs double rolls (53 cm x 10 m, about 57 sq ft)
- InteriorDecorating.com: how much wallpaper (27 in American double rolls, about 70 sq ft)
Sources last checked 1 November 2026.
Frequently asked questions
How many rolls of wallpaper do I need for an accent wall?
A 12 ft wide, 8 ft high wall takes 8 strips; with a 21 in repeat you get 3 strips from a 33 ft roll, so 3 double rolls plus a little extra.
What is a drop match?
The pattern lines up halfway down the next strip, so each strip is offset by half a repeat. It wastes a little more paper.