Wallpaper Calculator

The short answer

Count strips, not square feet. Divide the width of the walls by the roll’s width and round up for the strips. Each strip is the wall height plus about 4 in for trimming, rounded up to whole pattern repeats. Then see how many strips one roll gives, divide, round up, and add a spare roll.

A 12 × 15 ft bedroom with 8 ft walls takes 32 strips of 20.5 in paper, 8 ft 4 in each. A 33 ft roll gives 3 of them, so that’s 11 rolls and a spare: 12 rolls.

How to measure

1. The walls: measure each wall you’ll paper along the floor, corner to corner, and add them up. For a whole room, measure it wall to wall both ways.
2. The height: measure from the floor to the ceiling. If the walls aren’t all the same height, measure the highest point.
3. The roll: read its width, its length and the pattern repeat on the label. The repeat is also on the back of the sample.
4. Doors and windows: leave them in; see Doors and windows.

How to use the calculator

1. Choose a whole room or one wall, and enter its size and the height. A room you entered in another tool carries over.
2. Enter the roll’s width, length and pattern repeat from the label. Use 0 for a plain paper or a free match.
3. Check the extra length for trimming, 4 in unless your paper’s instructions say otherwise, and whether to add a spare roll.
4. Read the result: the rolls to buy, a cutting list and a drawing of the strips across your walls and one roll cut into strips.
5. Save or share it. Copy link keeps your numbers in the address.

How we calculate

The counts are estimates. If your paper’s product page has its own roll calculator, that comes first.

• Strips: the width of the walls divided by the roll’s width, rounded up. Strips run floor to ceiling, so there are no seams across the wall.
• Each strip: the wall height plus 4 in for trimming, about 2 in at the ceiling and 2 in at the baseboard, rounded up to whole pattern repeats. That way every strip starts at the same point in the pattern. Adding one whole repeat to the height instead usually comes to about the same.
• Strips per roll: the roll’s length divided by the strip’s, rounded down, since a short piece can’t make a strip.
• Rolls: the strips divided by the strips per roll, rounded up, plus one spare roll unless you turn it off.
• Doors and windows: left in, since you cut them out as you hang.

Worked examples

Worked example

A 12 × 15 ft bedroom with 8 ft ceilings, plain paper

What we know

• Room: 12 ft × 15 ft, 8 ft high (54 ft around)
• Rolls: 20.5 in × 33 ft, no pattern repeat

How it works out

1. Strips: 54 ft ÷ 20.5 in, rounded up = 32.
2. Each strip: 8 ft + 4 in for trimming = 8 ft 4 in.
3. Strips per roll: 33 ft ÷ 8 ft 4 in, rounded down = 3.
4. Rolls: 32 ÷ 3, rounded up = 11, plus 1 spare.

12 rolls of wallpaper: 11 rolls for 32 strips and a spare.

Worked example

A 10 ft accent wall with a 21 in pattern repeat

What we know

• One wall: 10 ft wide, 8 ft high
• Rolls: 20.5 in × 33 ft, 21 in pattern repeat

How it works out

1. Strips: 10 ft ÷ 20.5 in, rounded up = 6.
2. Each strip: 8 ft + 4 in for trimming, in whole 21 in repeats = 8 ft 9 in.
3. Strips per roll: 33 ft ÷ 8 ft 9 in, rounded down = 3.
4. Rolls: 6 ÷ 3, rounded up = 2, plus 1 spare.

3 rolls of wallpaper: 2 rolls for 6 strips and a spare.

Worked example

A 12 × 14 ft dining room, 9 ft high, in a large pattern

What we know

• Room: 12 ft × 14 ft, 9 ft high (52 ft around)
• Rolls: 27 in × 27 ft, 25.25 in pattern repeat

How it works out

1. Strips: 52 ft ÷ 27 in, rounded up = 24.
2. Each strip: 9 ft + 4 in for trimming, in whole 25.25 in repeats = 10 ft 6.25 in.
3. Strips per roll: 27 ft ÷ 10 ft 6.25 in, rounded down = 2.
4. Rolls: 24 ÷ 2, rounded up = 12, plus 1 spare.

13 rolls of wallpaper: 12 rolls for 24 strips and a spare.

Wallpaper rolls for common rooms

The strips and rolls for common room sizes with 8 ft walls, in 20.5 in × 33 ft rolls with no pattern repeat. Add one spare roll to each.

How many strips a roll gives

Full-height strips from three common rolls, with 4 in for trimming and no pattern repeat. A pattern repeat can only lower these.

The 27 in × 27 ft roll is a double roll, and 53 cm × 10 m is a metric roll. Standard widths are 21, 27 and 42 in.

Pattern repeat and match

• The repeat: how far the pattern runs before it starts again, from 0 to 23 in on most papers. Larger patterns can take more rolls to match.
• The match: free, straight or offset. A free match wastes the least, since the strips line up any way. A straight match lines up across in a straight line, and a drop match in a V.
• Half-drop designs: every other strip shifts by half the repeat. Panels printed to length may need to be longer for them, so follow the maker’s calculator for a half-drop panel.
• Working from two rolls at once sometimes cuts down on waste when matching a pattern.

Doors and windows

The calculator measures right across doors and windows. There’s no need to deduct them: you cut them out as you hang, and leaving them in gives just the right amount of extra for mistakes.

Over a wide opening, you can take off the whole strips that fit across it. You’ll buy a little less, with less to spare for mistakes.

Buying the rolls

• Double rolls: wallpaper is often priced by the single roll but sold in double or triple rolls. Enter the length of the roll you’ll actually get.
• One run or lot: check that every roll has the same run or dye lot number, since the color can vary between batches.
• A spare roll: one, or two to be safe, for trimming, mistakes and patches later.

Before you hang

• The wall: clean, smooth and sound, with old wallpaper removed. For unpasted paper, put on a wallpaper primer or sealer first.
• Booking: fold a pasted strip onto itself for several minutes so it relaxes before it goes on the wall. Your paper’s instructions give the time.
• Trimming: 4 in of extra length per strip. Peel and stick can take less, 2 to 3 in, and pasted paper more, 6 to 8 in, so set the trim to match yours.

Then paint the other walls with the paint calculator, or pick the colors first with the room color palette generator.