Wallpaper Calculator

This wallpaper calculator tells you how many rolls to buy for a whole room or a single accent wall. Instead of dividing wall area by roll coverage, it counts the vertical strips you will actually hang, works out how many full strips each roll yields, and allows for doors, windows and the pattern repeat printed on the label.

You can enter a room as length and width or type the total width of the walls you are papering. Roll sizes are preset for a US double roll (20.5 in x 33 ft), a standard euro roll (53 cm x 10.05 m) and a wide roll, or you can enter any custom size in US or metric units.

How to Use the Wallpaper Calculator

1
Choose units
Pick US (feet and inches) or Metric (meters and centimeters). The door, window and roll defaults switch to match.
2
Enter the walls
Choose Whole room and enter the room length and width, or choose Wall width and enter the combined width of the walls you are covering. Then enter the wall height.
3
Add doors and windows
Enter how many doors and windows the walls have and adjust their width and height if they differ from the defaults. Set a count to 0 to skip it.
4
Set the roll size and pattern repeat
Pick a roll size or type the width and length from the label, then enter the pattern repeat. Use 0 for plain or random-match paper.
5
Read the result
The calculator shows the rolls to buy, the number of strips, full strips per roll, the cut length of each strip and the net wall area.

How the wallpaper calculator works

Wallpaper is hung in full-height strips (also called drops), and any paper left at the end of a roll that is shorter than one strip is usually wasted. That is why this tool uses the strip method rather than dividing the wall area by the area of a roll.

First it finds the width to cover: the room perimeter, or the wall width you entered. Doors and windows are deducted as an equivalent width, their total area divided by the wall height. The net width divided by the roll width, rounded up, gives the number of strips.

Each strip is cut to the wall height plus a trimming allowance of 4 in (10 cm in metric), 2 in at the top and 2 in at the bottom. When the paper has a pattern repeat, that length is rounded up to a whole number of repeats so every strip starts at the same point in the pattern. The roll length divided by the cut length, rounded down, is the number of full strips per roll. Strips divided by strips per roll, rounded up, is the number of rolls.

Net width = wall width − (door and window area ÷ wall height)
Strips = net width ÷ roll width (round up)
Cut length = wall height + 4 in, rounded up to a whole pattern repeat
Strips per roll = roll length ÷ cut length (round down)
Rolls = strips ÷ strips per roll (round up)

Worked example: a 12 x 14 ft bedroom

The room has 8 ft walls, one 3 x 7 ft door and two 3 x 4 ft windows. You are using US double rolls (20.5 in x 33 ft, which is 396 in) with a 21 in pattern repeat.

Perimeter: 2 x (14 + 12) = 52 ft, or 624 in.
Openings: 21 + 24 = 45 sq ft, or 6,480 sq in. Divided by the 96 in wall height, that is 67.5 in of width.
Net width: 624 − 67.5 = 556.5 in.
Strips: 556.5 ÷ 20.5 = 27.15, rounded up to 28 strips.
Cut length: 96 + 4 = 100 in. With a 21 in repeat, 100 ÷ 21 = 4.76, rounded up to 5 repeats, so each strip is 105 in (8 ft 9 in).
Strips per roll: 396 ÷ 105 = 3.77, rounded down to 3.
Rolls: 28 ÷ 3 = 9.33, rounded up to 10 double rolls.

Metric example: a 4 x 3.5 m room

The walls are 2.5 m high with one 0.9 x 2.1 m door and one 1 x 1.2 m window. You are using standard euro rolls (53 cm x 10.05 m) with a 53 cm repeat.

The perimeter is 15 m (1,500 cm). The openings total 3.09 m², which is 123.6 cm of width at a 250 cm wall height, leaving 1,376.4 cm. That needs 26 strips. Each strip is 250 + 10 = 260 cm, rounded up to 5 repeats of 53 cm, so 265 cm. A 1,005 cm roll gives 3 full strips, so you need 26 ÷ 3 = 8.67, rounded up to 9 rolls.

Cut length and strips per US double roll

This table shows how wall height and pattern repeat change the cut length and the number of full strips you get from one 20.5 in x 33 ft double roll, using the calculator's 4 in trim allowance. Notice how a 24 in repeat on a 10 ft wall drops the yield from 3 strips to 2.

Wall height	No repeat	12 in repeat	21 in repeat	24 in repeat
8 ft	100 in, 3 strips	108 in, 3 strips	105 in, 3 strips	120 in, 3 strips
9 ft	112 in, 3 strips	120 in, 3 strips	126 in, 3 strips	120 in, 3 strips
10 ft	124 in, 3 strips	132 in, 3 strips	126 in, 3 strips	144 in, 2 strips

Tips and common mistakes

Check the label for the roll size. US wallpaper is often priced per single roll but sold only in double rolls, so confirm what one unit contains before you order.
Buy every roll from the same batch or lot number. Colors can shift slightly between print runs.
Consider one spare roll for mistakes, future repairs and awkward areas such as around fireplaces or stairs.
Drop-match (half-drop) patterns can waste more paper than straight-match ones because alternate strips start half a repeat lower. If the label says drop match, an extra roll is a sensible buffer.
Small openings such as outlets and switches are not worth deducting. Very large openings, like a wide patio door, make a real difference, so enter them.
Measure every wall height separately in older homes. If heights vary, use the tallest one.

Features

Whole-room (length x width) or total wall width input
Deducts doors and windows with editable sizes
US double roll, standard euro roll, wide roll or custom roll sizes
Pattern repeat rounds each strip up to a whole repeat
Shows strips needed, strips per roll and cut length
US (ft, in) and metric (m, cm) units

Frequently Asked Questions

How many rolls of wallpaper do I need for a 12 x 12 room?

With 8 ft walls, one 3 x 7 ft door and one 3 x 4 ft window, a 12 x 12 ft room has 526.5 in of net wall width. On US double rolls (20.5 in x 33 ft) that is 26 strips. With no pattern repeat each strip is 100 in, a roll gives 3 strips, so you need 9 double rolls. A 24 in repeat raises the cut to 120 in but still gives 3 strips per roll, so it stays at 9.

How do I calculate wallpaper with a pattern repeat?

Add a trimming allowance to the wall height, then round that length up to a whole number of repeats. With 8 ft walls and a 4 in allowance, a strip is 100 in. For a 21 in repeat, 100 divided by 21 is 4.76, so round up to 5 repeats and cut each strip 105 in long. Then divide the roll length by the cut length and round down to get strips per roll.

How many rolls of wallpaper for an accent wall?

A 12 ft wide, 8 ft high accent wall with no openings is 144 in wide, which needs 8 strips of 20.5 in paper. With no repeat each strip is 100 in, so a 33 ft double roll yields 3 strips and you need 3 double rolls. A large repeat or a taller wall can lower the strips per roll, so enter your label values in the calculator.

What size is a double roll of wallpaper?

In the US, a common double roll is about 20.5 in wide and 33 ft long, which is roughly 56 sq ft of paper. A standard euro roll is 53 cm wide and 10.05 m long, about 5.3 m². Sizes vary by brand and some papers are 27 in wide, so always check the label before you calculate.

Why not just divide the wall area by the roll coverage?

Because the offcut at the end of each roll is usually too short for another full strip. In the 12 x 14 ft example, 371 sq ft of wall divided by 56.4 sq ft per double roll suggests about 7 rolls, but hanging 28 strips of 105 in with 3 strips per roll actually takes 10. The strip method gives a figure you can hang without running short.

Should I subtract doors and windows from wallpaper?

Yes for doors and larger windows, since they can save a strip or two. This calculator converts their area into an equivalent wall width and subtracts it before counting strips. Skip small items such as outlets. If the room has many small openings, it is fine to deduct less and keep the extra paper as a spare.

Last reviewed September 21, 2026