The Build Calculator

Wallpaper Calculator

Calculate how many rolls of wallpaper you need — with the pattern repeat properly accounted for. Works for US double rolls and metric rolls, walls or whole rooms.

Sum of all walls being papered

Printed on the roll label

Wallpaper needed (+1 spare recommended)
rolls
strips to hang
strips per roll
cut length per strip

Enter a price per roll to estimate cost.

You might also need:Paint Calculator·Drywall Calculator

How professionals count wallpaper

strips = wall width ÷ roll width · cut length = wall height + 4″ trim + repeat allowance
strips per roll = floor(roll length ÷ cut length) · rolls = strips ÷ strips per roll

Strip counting beats square-foot math because it mirrors how paper is actually cut: each strip needs trim at top and bottom plus up to one pattern repeat to match its neighbor. A 12-foot wall in metric rolls is 8 strips; at 8-foot ceilings with a 12-inch repeat each roll yields 3 strips → 3 rolls.

Rolls needed by wall size (metric roll, ≤12″ repeat, 8 ft ceiling)

Wall widthStripsRolls
6 ft (small accent)42
12 ft (accent wall)83
24 ft (two walls)155
48 ft (whole room)2910

Hanging tips

  • Start in the least visible corner — the final seam almost never pattern-matches.
  • Plumb line first: walls aren't straight; hang the first strip to a level line, not the corner.
  • Peel-and-stick vs traditional: same math applies — peel-and-stick just forgives repositioning.
  • Painting the other walls? Head to the paint calculator; fresh drywall math is in the drywall calculator.

Frequently asked questions

How much does a roll of wallpaper cover?+

An American double roll (27 inches × 27 feet) covers about 57 usable square feet after trimming; a European/metric roll (20.5 inches × 33 feet) covers about 48 square feet. Pattern repeat reduces usable coverage further — that is why this calculator asks for it.

What is pattern repeat and why does it matter?+

Pattern repeat is the vertical distance before the design repeats. Every strip must start at a matching point, so you waste up to one repeat per strip. A 24-inch repeat can cost you 15–25% extra paper versus a plain paper — never skip it in your math.

How many rolls do I need for one accent wall?+

A typical 12 × 8 ft accent wall needs 5–6 strips. With a standard 20.5-inch metric roll at 33 ft you get 3 strips per roll (8 ft walls, small repeat) — so 2 rolls, or 3 with a large pattern repeat. Always round up; dye lots vary.

Do I subtract windows and doors when calculating wallpaper?+

Only subtract very large openings. Strips still run full height beside and above openings, and the offcuts are rarely reusable because of pattern matching. Standard practice: ignore normal doors and windows and keep the safety margin.

Should I order all rolls at once?+

Yes — wallpaper is printed in batches ("dye lots") and colors shift subtly between lots. Order every roll plus one spare from the same lot number; a mismatched replacement roll on the same wall is obvious.

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