What does this tool do?
Wallpaper is ordered in rolls, with coverage depending on the roll width and length. This calculator deducts large openings, applies a 10% waste allowance and divides by the coverage of one roll.
The Formula
Rolls = ⌈(Perimeter × Height − Openings) × (1 + Waste ÷ 100) ÷ Roll coverage⌉Frequently Asked Questions
How many rolls for a 40 ft room?
With 9 ft walls and 50 sq ft of openings, a 56 sq ft double roll needs about seven rolls including waste.
How does pattern repeat affect rolls?
Large repeats force more waste at each drop. Add 15–25% when the repeat is over 12 in.