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Drywall, Flooring & Interior

Wallpaper Calculator

Rolls of wallpaper for a room, worked out strip by strip so the pattern repeat is accounted for rather than averaged away.

Your measurements

Wallpaper is estimated by whole strips, not by area — a repeat wastes paper at the top of every drop.

The room
Doorways and patio doors. Windows are not deducted — you still hang strips above and below them.
The paper
Printed on the roll label. Enter 0 for a plain or random match paper.

Your result

Sample values

10

Rolls

27

Strips needed

3

Strips per roll

119

Cut length, in

48 ft perimeter less a 3 ft doorway, 8 ft walls, 19 in repeat, 10% waste.

How the repeat costs you

Pattern repeat Strips per 33 ft roll
0 in — random match 3
6 in 3
19 in 3
24 in 2

How to use this calculator

Measure right around the room including doorways, then take the doorway widths off separately. Enter the roll length and width from the label rather than assuming — European rolls are commonly 33 ft by 20.5 in, but American rolls and designer papers vary a lot.

The pattern repeat is the number that catches people out. Each strip has to start at the same point in the pattern, so on a 19 inch repeat you can lose up to 19 inches off the top of every drop. Enter zero only if the label says random or free match.

Formula

Cut length = Wall height + Pattern repeat + 4 in trim

Strips per roll = floor(Roll length ÷ Cut length)

Strips needed = ceil((Perimeter − Openings) ÷ Roll width)

Rolls = ceil(Strips ÷ Strips per roll × (1 + Waste))

Cut length
what you actually cut for one drop, repeat included
4 in
trim allowance, two inches top and bottom

Strips per roll floors — a part strip left on the roll cannot reach the ceiling.

Worked example

A room 48 ft around with one 3 ft doorway, 8 ft walls, 19 in repeat, 33 ft × 20.5 in rolls.

  1. Papered perimeter: 48 − 3 = 45 ft, or 540 in
  2. Cut length: 96 + 19 + 4 = 119 in
  3. Strips per roll: floor(396 ÷ 119) = 3
  4. Strips needed: ceil(540 ÷ 20.5) = 27
  5. Rolls: ceil(27 ÷ 3 × 1.10) = 10

10 rolls

Understanding your results

Estimating wallpaper by area is the classic mistake. A roll advertised as covering 56 square feet only does so with no repeat and no wastage; with a 19 inch repeat on an 8 foot wall you get three usable drops out of it instead of four, so the effective coverage falls by a quarter before any trimming.

Buy every roll in one go and check the batch numbers match. Dye lots vary enough to be visible on a wall, and a roll bought a month later almost never matches. Running one roll short is far more expensive than ordering one spare.

Questions

About this calculator

Ask something else

Because every strip has to start at the same point in the pattern to line up with its neighbour. On a 19 inch repeat you may waste up to 19 inches off the top of each drop getting to that point. The longer the repeat, the fewer full drops you get from a roll.

No, and this calculator does not. You still hang a strip above and below a window, and the offcut from the middle is rarely usable elsewhere. Only full height openings such as doorways come off the perimeter.

A straight match repeats at the same height on every strip. A drop match offsets alternate strips by half the repeat, so the pattern runs diagonally. A drop match usually wastes more, so add a little extra on top of the calculated figure.

Ten percent is built in here, and one spare roll on top is cheap insurance. Keep it — future repairs need paper from the same batch, and by the time you need it the pattern may be discontinued.

Keep going

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Estimates, not specifications. Results are based on the values you enter and on typical material properties. Densities, coverage rates and product sizes vary between suppliers, so confirm quantities against your supplier's data before ordering. Structural work must be signed off by a qualified professional and meet your local building code.