Why does the pattern repeat change how much I need?
Each strip must be cut so the pattern aligns, wasting up to one full repeat per drop. A 21 in repeat can add 15–25% to the roll count.
Calculate the number of wallpaper rolls needed for any room. Accounts for pattern repeat, doors, windows, and waste.
Rolls = ceil(wall area × (1 + pattern waste) ÷ usable roll coverage). Usable coverage falls as pattern repeat rises.
A room with 400 sq ft of wall and a double roll covering 56 sq ft needs 8 rolls plain, but 9–10 with a 21 in pattern repeat.
Each strip must be cut so the pattern aligns, wasting up to one full repeat per drop. A 21 in repeat can add 15–25% to the roll count.
A single roll covers about 28 sq ft usable and a double roll about 56 sq ft, after trimming and pattern matching from the printed 56/70 sq ft.
Yes, from the same batch or dye lot. Colours drift noticeably between print runs, and a late extra roll often will not match.