Wallpaper Calculator

How to use this tool

Enter the room’s length and width and the wall height, or type the total width of wall you are papering if it is a single feature wall. Add the number of doors, pick the roll size from the label, and enter the pattern repeat and match type if the paper has a pattern. The number of rolls appears at the top, with the drops, the drops per roll and the offcut.

The first drawing shows how one roll is cut into drops and how much is left over; the second unrolls the walls into one strip and numbers each drop by the roll it comes from. The table compares the roll sizes for the same walls.

How the rolls are counted

Decorators count wallpaper in drops, the full height lengths hung side by side. The number of drops is the width of the walls divided by the width of the roll, rounded up. Each drop is the wall height plus about 4 in for trimming top and bottom, and if the paper has a pattern it is rounded up to a whole number of repeats so that the pattern lines up across the join.

Only whole drops can be cut from a roll, so the roll length divided by the drop length, rounded down, is the number of drops per roll. The drops needed divided by the drops per roll, rounded up, is the number of rolls. Doors are taken off at 3 ft each; windows are left in, because the short pieces above and below them use nearly as much paper as a full drop.

Rolls for common rooms

Standard 20.5 in x 33 ft rolls, no pattern repeat, no doors taken off. The last column shows how far dividing by area alone falls short.

Roll sizes

The standard roll is sold as 53 cm x 10.05 m in Europe and about 20.5 in x 33 ft in the US.

Most wallpaper sold in Europe, and much of it in the US, comes on the standard 53 cm by 10.05 m roll, about 20.5 in by 33 ft. American papers are often priced by the single roll but only sold in double rolls; a double roll of 27 in paper is about 27 ft long. Wide rolls of 70 cm or more cover more wall per drop and mean fewer seams.

A worked example you can check on paper

A bedroom is 12 by 14 ft with 8 ft walls. The wall around the room is 2 times 26, 52 ft, which is 624 in. With a 20.5 in roll that is 30.4 drops, so 31. Each drop is 8 ft plus 4 in, 8 ft 4 in, and a 33 ft roll holds three of them with 8 ft left over. 31 drops divided by 3 is 10.3, so buy 11 rolls.

If the room has one door, the wall is 49 ft and 29 drops, which is 10 rolls. If the paper has a 21 in half drop repeat, each drop grows to 9 ft 7.5 in; a roll still gives three, so the count does not change at this height. On 9 ft walls the same half drop paper gives only two drops a roll, and the room needs 16 rolls.

Pattern matches

Random match. Stripes and textures with no pattern to line up; drops can be cut in any order and waste is lowest.

Straight match. The pattern lines up straight across every drop, so each drop starts at the same point in the repeat.

Half drop. Every other drop is shifted down by half a repeat, which creates a diagonal pattern and uses the most paper. Many decorators hang from two rolls at once to reduce the waste.

Mistakes that catch people out

Working from area alone. It ignores the offcut at the end of every roll and comes up short.

Ignoring the repeat. A large repeat can cut a roll from three drops to two on the same wall.

Mixing batches. Check the batch number on every label; slight color differences show on the wall.

Measuring only the flat walls. Include chimney breasts, alcoves and returns around the edge of the room.

Starting in the wrong place. Hang from the least visible corner so the last drop, where the pattern rarely meets, is out of sight.

Popular calculations

Each opens the calculator with its own address, and every value can be changed once it is open.

Rooms with 8 ft walls

Rooms with 9 ft walls

Feature walls

Metric rooms and walls

Patterned paper

How this was checked

The engine was tested in Node against drop counts worked by hand: a 12 by 14 ft room with 8 ft walls gives exactly 31 drops of 8 ft 4 in, three per 33 ft roll and 11 rolls; one door takes it to 29 drops and 10 rolls; a 21 in half drop repeat gives 9 ft 7.5 in drops; and a 3 by 4 m room with 2.4 m walls gives 27 drops, four per 10.05 m roll, and 7 rolls. Walls taller than a roll and doors wider than the wall are caught with a message.

Every address in the lists above was then opened and checked for a distinct title, the right answer, drawings that render, and clean CSV, image and print output containing only that calculation, at desktop, tablet and phone widths.

Common questions

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

With 8 ft walls a 12 by 12 ft room has 48 ft of wall, which takes 29 drops of a standard 20.5 in roll. Each 33 ft roll gives three drops of 8 ft 4 in, so you need 10 rolls. Take off a drop or so for each door, and add rolls for a large pattern repeat.

How do you calculate wallpaper rolls?

Divide the width of the walls by the roll width and round up to get the number of drops. Add about 4 in to the wall height for trimming, round up to a whole number of pattern repeats, and see how many of those drops fit whole on one roll. Drops needed divided by drops per roll, rounded up, is the number of rolls.

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

Because only whole drops can be cut from a roll. On an 8 ft wall a 33 ft roll gives three drops and leaves about 8 ft of offcut that cannot make a fourth. Area alone ignores that and usually comes out three or four rolls short for a bedroom.

What is a pattern repeat and a half drop?

The repeat is the distance before the pattern starts again down the roll. With a straight match each drop starts at the same point in the pattern; with a half drop every other drop is shifted by half a repeat, which wastes more paper. Both are printed on the label.

How much does a roll of wallpaper cover?

A standard 20.5 in by 33 ft roll is about 56 sq ft, and a 27 in by 27 ft double roll about 61 sq ft. After trimming, a standard roll covers about 40 sq ft of wall on 8 ft walls, three drops of 20.5 in, and less with a large repeat.

Should I buy extra wallpaper?

Yes, at least one spare roll from the same batch. Rolls from different print runs can differ slightly in color, and a spare is the easiest way to repair damage later.

Related Calculators and Reference

• Paint Coverage Calculator: for the ceiling and trim, or walls you paint instead.
• Square Footage Calculator: for rooms that are not simple rectangles.
• Carpet Calculator: square yards of carpet for the same room.
• Drywall Calculator: sheets, tape and compound if the walls need replacing first.
• Length Converter: roll sizes in inches, feet, centimeters and meters.
• Houzz: shopping for wallpaper: single, double and European rolls and pattern matches explained.