BuildCalcs

Wallpaper Calculator — With Pattern Repeat

By BuildCalcs · Updated

Enter your room size, roll dimensions, and — crucially — the pattern repeat. Patterned wallpaper must be cut so each strip starts at the same point in the design, which increases waste. This calculator handles that correctly.

US rolls ≈20.5 in; European ≈20.9 in (53 cm).

US single roll ≈33 ft; European ≈33 ft (10 m).

The vertical distance before the design repeats. 0 for plain/random match.

Rolls needed9 rolls
Strips (drops) needed26 strips
Usable strips per roll3 strips
Length per strip8.33 ft

How to use this calculator

  1. Enter the room length, width, and wall height in feet.
  2. Enter the roll width and length from the wallpaper specs.
  3. Enter the pattern repeat — the most important field. Find it on the product page; use 0 only for plain paper or a free/random match.
  4. The calculator rounds each strip up to a full repeat so patterns line up, then works out the rolls.

The formula

Wallpaper is hung in vertical strips (drops), so we count strips, not area.

Strips needed = room perimeter ÷ roll width. Perimeter = 2 × (length + width).

Drop length = wall height + trim, then rounded UP to a whole pattern repeat — this is the step that wastes paper on patterned designs. A 25 in repeat forces every 8 ft 4 in drop up to the next multiple of 25 inches.

Strips per roll = roll length ÷ drop length (rounded down). Rolls = strips needed ÷ strips per roll (rounded up).

Worked example

A 12 ft × 10 ft room, 8 ft walls, 20.5 in × 33 ft rolls, 21 in pattern repeat.

  1. Perimeter = 2 × (12 + 10) = 44 ft
  2. Strips = 44 ÷ (20.5 ÷ 12) = 44 ÷ 1.71 = 25.7 → 26 strips
  3. Drop = 8 + 0.33 = 8.33 ft, rounded up to a 21 in (1.75 ft) repeat → 8.75 ft
  4. Strips per roll = 33 ÷ 8.75 = 3.77 → 3 strips
  5. Rolls = 26 ÷ 3 = 8.67 → 9 rolls

With a 21 in repeat you need 9 rolls — versus 7 for a plain paper. The repeat is why.

Frequently asked questions

Why does the pattern repeat increase how much wallpaper I need?

Each strip must start at the same point in the design so neighboring strips line up. That means cutting every strip to a whole number of repeats, so part of each strip is trimmed off and wasted. The bigger the repeat, the more waste.

Where do I find the pattern repeat?

It is listed in the wallpaper specifications, often labeled "pattern repeat" or "vertical repeat," in inches or centimeters. Plain papers and "random match" papers have effectively no repeat — enter 0.

How many rolls of wallpaper do I need for a room?

Measure the perimeter, divide by the roll width to get the number of strips, find how many full strips come from one roll (allowing for the repeat), then divide. This calculator does all of that for you.

Should I subtract doors and windows?

For small openings it is safest not to — the offcuts rarely yield a full usable strip, and the extra becomes spare paper for repairs. Only deduct strips for very large openings.

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