StructureCalculator

Wallpaper Calculator

Walls
Wallpaper roll
Pattern
Order & cost
Wallpaper
Rolls to buy—
Rolls before spares—
Strips—
Strip length—
Strips per roll—
Wall area—
Waste—
Wallpaper cost—
Total cost—

Estimate from your measurements. The roll size, repeat, and offset on the label take priority over these defaults.

Count wallpaper in whole strips, not square feet. A 12 × 10 ft room with 8 ft walls takes 26 strips of 20.5 in paper. A 33 ft double roll yields 3 strips, so you need 9 rolls, or 10 with a spare. A large pattern repeat or a half-drop match can add more. Enter your room, roll, and pattern below.

How many rolls of wallpaper for your room?

Rolls before any spare, using a 20.5 in × 33 ft double roll and 4 in of trim per strip, with doors and windows not deducted. A roll gives 4 strips on 7.5 ft walls, 3 on 8 ft and 10 ft walls, and 2 on 10 ft walls with a 24 in half-drop.
RoomStrips7.5 ft walls8 ft walls10 ft walls10 ft, 24 in half-drop
10 × 10 ft2468812
12 × 10 ft2679913
12 × 12 ft298101015
15 × 12 ft328111116
20 × 12 ft3810131319
20 × 15 ft4111141421

How to calculate wallpaper rolls

Wallpaper goes up in vertical strips, so strips decide the order. There are three steps:

  • Strips: wall width or room perimeter ÷ roll width, rounded up.
  • Strips per roll: roll length ÷ strip length, rounded down. Strip length is the wall height plus trim.
  • Rolls: strips ÷ strips per roll, rounded up.

A 12 × 10 ft room has a 44 ft perimeter, or 528 in. 528 ÷ 20.5 = 25.8, so 26 strips. On 8 ft walls with 4 in of trim, each strip is 100 in. A 33 ft roll is 396 in, and 396 ÷ 100 = 3.96, so 3 whole strips per roll. 26 ÷ 3 = 8.67, so 9 rolls.

Why the square-foot method comes up short

The common shortcut divides wall area by roll area: 352 ÷ 56 = 6.3, so 7 rolls. That only works if every offcut can go on the wall. Here, each roll ends with 96 in left over, too short for another full strip with trim. You can use some of those pieces above doors and below windows, but don't count on them, especially with a patterned paper.

Standard 8 ft walls sit right on the line

That 3.96 is worth a second look. With 4 in of trim, a 33 ft roll misses a fourth strip by just 4 in. With 3 in of trim on perfectly even 8 ft walls, each strip is 99 in, you get 4 strips per roll, and the same room takes 7 rolls instead of 9. Trimming that tight leaves no room for an uneven ceiling, so 4 in is the safer default. On 7.5 ft walls, 4 strips fit comfortably. The table above shows how height changes the count.

Wallpaper with a pattern repeat

The repeat is the distance before the design starts again. For the pattern to line up, each strip has to be a whole number of repeats long. You'll find the repeat and match type on the label or the product page.

  • Random match: No alignment needed, as with grasscloth, plain paper, or many textures. Only height and trim count.
  • Straight match: The design sits at the same height on every strip. Take (height + trim) ÷ repeat, round up, and multiply by the repeat.
  • Half-drop match: Every other strip drops by half the repeat. Add the offset before you divide: (height + trim + offset) ÷ repeat, round up, and multiply by the repeat.

Here's a half-drop with a 21 in repeat on 8 ft walls: 96 + 4 + 10.5 = 110.5 in. 110.5 ÷ 21 = 5.26, which rounds up to 6, so each strip is 126 in and a roll yields 3. A 24 in half-drop on 10 ft walls is the costly case. 120 + 4 + 12 = 136 in, which rounds up to 144 in, so a roll yields only 2 strips and a 20 × 15 ft room goes from 14 rolls to 21.

Cut the first strip with these numbers and use it as your template. On a half-drop, the position repeats every second strip.

Wallpaper roll sizes

US wallpaper is usually sold in double rolls of about 20.5 in × 33 ft, or roughly 56 square feet. A European roll is 53 cm × 10.05 m, which is nearly the same. Some sellers use wider 27 in rolls, and peel-and-stick sizes vary widely. The presets above cover the common cases, and you can type any other size.

Watch for single-roll pricing. Many brands quote a price per single roll but ship double rolls, so the "single roll" count on a product page may be twice the number of bolts you receive. Enter the size you'll actually get and the price of that size.

Doors, windows, and sloped walls

The calculator only subtracts doors and windows if you enter their width. It's usually better to leave them in, because the short pieces above and below them are hard to reuse. Subtracting makes sense for a wall of windows or a sliding glass door. Add window reveals to the wall width if you plan to paper them.

For an accent wall, switch to One wall. For a stairwell or a sloped ceiling, measure the longest strip and use that as the height. The calculator can't credit the offcuts from the short side, so check those walls by hand. Murals are ordered by the panel, so this calculator doesn't apply. For plain wall area to compare paint or get a quote, use the square footage calculator.

How much does wallpaper cost to install?

For a DIY job, you pay for paper, plus paste if the paper needs it and a few tools. Enter your price per roll to see the paper cost. For a pro, Taskrabbit puts US labor at about $2 to $6 per square foot for standard paper and $6 to $14 for grasscloth and murals, with minimum fees often at $150 to $300. Pattern repeats, stairwells, and wall prep can all raise the price. At $3 per square foot, a 352 square foot room is about $1,056 in labor. Ask whether removing old paper and repairing walls are included. The calculator multiplies your rate by the wall area only.

Common mistakes

  • Ordering by square feet alone. Area math tends to come up short. Work in strips.
  • Forgetting the repeat. A long repeat can cost you a strip on every roll, which adds several rolls across a room.
  • Mixing production runs. Color can shift between runs. Check the batch or dye lot number on each label and buy every roll at once.
  • Skipping the spare. One miscut on the last strip is enough, and a later order may not match. One or two spares are common, and the calculator starts at one.
  • Measuring the height once. Older homes are rarely the same height all the way around, so use the tallest measurement.

The formulas come from the guides listed under Sources, and the roll counts in the table and examples come directly from this calculator. The labor figures are rough ranges from a cost guide, not quotes.

Frequently asked questions

How do I calculate how much wallpaper I need?

Divide the wall width by the roll width and round up to get strips. Divide the roll length by the strip length and round down to get strips per roll. Strips ÷ strips per roll, rounded up, is the number of rolls. A 12 × 10 ft room with 8 ft walls takes 26 strips and 9 double rolls.

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

About 10 double rolls with 8 ft walls, before a spare, using 20.5 in × 33 ft rolls and 4 in of trim. That is 29 strips at 3 strips per roll. Shorter walls can need fewer rolls, because 7.5 ft walls fit 4 strips per roll.

How many square feet does a roll of wallpaper cover?

A 20.5 in × 33 ft double roll holds about 56 square feet. Expect less on the wall, because only whole strips count. On 8 ft walls a roll gives 3 strips, or about 41 square feet of wall.

What is the difference between a single roll and a double roll?

A double roll is one continuous piece twice the length of a single roll, commonly about 33 ft against 16.5 ft at 20.5 in wide. Many US brands quote the price per single roll but ship double rolls, so check which one the price and the coverage refer to.

What is a pattern repeat?

It is the distance before the design starts again. Each strip has to be long enough for the pattern to line up with the next one, so strip length rounds up to a whole number of repeats. It is printed on the roll label or the product page.

How much extra do I need for a half-drop match?

Add half the repeat to the height and trim before rounding up to whole repeats. With 8 ft walls, 4 in of trim, and a 21 in repeat, that is 100 + 10.5 = 110.5 in, which rounds up to 126 in. With a 24 in repeat the result often stays the same, so run your own numbers.

Should I subtract doors and windows?

Usually not. The pieces above doors and below windows are hard to reuse, and leaving them in gives you a small margin. For a wall of large windows, enter their total width in the calculator. Measure into window reveals if you plan to paper them.

How many extra rolls of wallpaper should I buy?

Buy one or two spares for miscuts and later repairs. Order every roll from the same production run, because color can shift between runs. The batch or dye lot number is printed on the label, and a later order may not match.

How much does it cost to have wallpaper installed?

Taskrabbit puts US labor at about $2 to $6 per square foot for standard paper and $6 to $14 for grasscloth and murals. Minimum fees often run $150 to $300, and removing old paper or repairing walls can add to the price. Get local quotes before you budget.

Why does the square-foot method give fewer rolls?

Dividing wall area by roll area assumes every inch of the roll ends up on the wall. In practice, the end of each roll is too short for another full strip. On 8 ft walls that leaves about 8 ft per double roll, so the strip method is the realistic one.

Sources