How to use the wallpaper calculator
- Enter the room's length and width, or switch to Total wall width if you are papering one wall or a few. Add the wall height at its highest point.
- Enter the number of doors and windows. Their sizes are under the optional settings; change them to yours.
- Pick the roll size and enter the pattern repeat from the label or product page. Use 0, or choose a free match, for plain or random-match paper.
The result updates as you type. It shows the rolls by the strip method, and the simpler area estimate underneath for comparison.
How the strip method works
Wallpaper is hung in vertical strips (also called drops or lengths), and each strip has to be cut from one roll. So the question is how many whole strips a roll gives you, and how many strips go around the room.
- Strip length = wall height + pattern repeat. The extra repeat lets you slide each strip up or down to line up the pattern with the one next to it. A free match paper needs no extra.
- Strips per roll = roll length / strip length, rounded down. A part strip at the end of a roll is too short to use on a full-height wall.
- Strips needed = total wall width / roll width, rounded up. Doors and windows only save a strip when they are wider than a whole strip of wall, since you still paper above doors and around windows.
- Rolls = strips needed / strips per roll, rounded up.
Farrow & Ball, the paint and wallpaper maker, gives the same kind of rule of thumb for its rolls, which are "10m long and 53cm wide". For a standard 2.4 m room it estimates "Three drops per roll for small pattern repeats" and "Four drops per roll for striped papers". By the formula, a 2.4 m wall gives 4 strips from a 10 m roll with no repeat, and 3 strips with any repeat from about 10 cm to 93 cm.
Worked example: a 4 x 3.5 m room
A room 4 m by 3.5 m with walls 2.4 m high, one door (0.9 x 2.1 m) and one window (1.2 x 1.2 m), papered with standard 0.53 x 10.05 m rolls with a 53 cm straight match:
| Step | Working | Result |
|---|---|---|
| Wall width | 2 x (4 + 3.5) | 15 m |
| Strip length | 2.4 + 0.53 | 2.93 m |
| Strips per roll | 10.05 / 2.93 = 3.43, round down | 3 |
| Strips around the room | 15 / 0.53 = 28.3, round up | 29 |
| Less door and window | 3.33 m² / (0.53 x 2.4) = 2.6 whole strips | -2 |
| Rolls | 27 / 3 = 9 | 9 |
The same room in feet: 12 x 10 ft, 8 ft high, one 3 x 7 ft door, two 3 x 4 ft windows and US double rolls of 20.5 in x 33 ft with a 20.5 in repeat. Each strip is 116.5 in, a double roll gives 3, and 26 strips less 3 for the openings is 23: 8 double rolls (often priced as 16 single rolls). Separate single rolls of 16.5 ft give only one strip each here, so you would need 23.
Why the area estimate comes out lower
The quick method divides the wall area by the area of one roll. For the room above that is 36 m² less 3.33 m² for the door and window, 32.67 m², plus 10% extra, 35.94 m². One roll covers 0.53 x 10.05 = 5.33 m², so 35.94 / 5.33 rounds up to 7 rolls, two fewer than the strip method.
The gap is the end of every roll. Each roll here gives three strips of 2.93 m and leaves 1.26 m that is too short for another full strip. The area method counts that offcut as usable wall cover, so it runs short, especially with tall walls or large repeats. The strip method is how decorators count, and it is the figure to buy. The area estimate is still shown because it is what many product pages quote as coverage, such as "about 56.4 square feet" for a York double roll.
Roll sizes: UK, European and US
| Roll | Size | Area |
|---|---|---|
| Standard UK and European roll | 0.53 x 10.05 m (20.9 in x 33 ft) | 5.33 m² |
| US double roll | 20.5 in x 33 ft | 56.4 sq ft |
| US single roll | 20.5 in x 16.5 ft | 28.2 sq ft |
Boråstapeter, a Swedish wallpaper maker, says its roll width "is usually 53 cm" and the roll "is usually 10.05 metres long". York Wallcoverings lists US double rolls at "20.5in x 33.0ft". In the US, a double roll "is the equivalent length of two single rolls on one physical roll", and "Many manufacturers sell wallpaper by the single roll but ship by the double roll", as the retailer DecoratorsBest explains, so a price per single roll usually means you buy them in pairs. It also notes "There is no universal measurement for a single roll", and some papers are 27 in wide, so choose Other size and type the size on your label when it differs.
Waste, spare rolls and batches
- With a pattern repeat, the strip method covers matching waste and roll ends. For plain paper, leave a few centimeters at the top and bottom of each strip for trimming. The extra percentage only changes the area estimate. Graham & Brown advises: "You always want to measure for an extra 10% of waste."
- Doors and windows: Graham & Brown says "Excluding the doors and windows from your measurement should give you just the right amount of excess." To follow that, set doors and windows to 0. This calculator only takes off whole strips, so the difference is small.
- Buy a spare roll. Farrow & Ball recommends "adding one more roll to allow for trimming or mistakes when hanging".
- Buy one batch. Colors can vary between production runs; Farrow & Ball notes "the pattern and colour can differ oh-so-slightly between batches." Check that every roll has the same batch number.
- Half drop papers line up with an offset, so every other strip may start part way down the repeat. The calculator allows one full repeat per strip, which normally covers it, but a spare roll is wise.
Questions and answers
How many rolls of wallpaper do I need for a 12 x 12 room?
With 8 ft walls and US double rolls of 20.5 in x 33 ft: the walls are 48 ft around, so 29 strips. With no repeat, a roll gives 4 strips of 8 ft, so 8 double rolls before any doors and windows; with a 20.5 in repeat it gives 3, so 10. Enter your doors, windows and repeat for your own figure.
How many strips of wallpaper are in a roll?
Divide the roll length by the wall height plus the pattern repeat and round down. A 10.05 m roll on a 2.4 m wall gives 4 strips with no repeat and 3 strips with a repeat of about 12 cm to 95 cm.
How much does a roll of wallpaper cover?
A standard 0.53 x 10.05 m roll is about 5.3 m² (57 sq ft), and a US double roll of 20.5 in x 33 ft is about 56 sq ft. You get less usable cover than that because of pattern matching and the offcut at the end of each roll.
What is the difference between a single and a double roll?
In the US a double roll is two single rolls on one physical roll. Many brands quote prices per single roll but only sell double rolls, so order an even number of single rolls.
Should I subtract doors and windows when measuring for wallpaper?
Graham & Brown suggests leaving them in so you have some spare. This calculator takes off only whole strips of wall, because you still need paper above doors and below windows.
How much extra wallpaper should I buy?
The strip method already allows for pattern matching and roll ends. On top of that, buy one spare roll from the same batch for mistakes and later repairs.
Sources
Checked on 22 October 2026. If a rule has changed, please tell us.
- Farrow & Ball: Calculating wallpaper quantities
- Graham & Brown: How to measure your room for wallpaper
- Boråstapeter: How many rolls do you need? (roll width and length)
- York Wallcoverings: Colette Modern wallpaper (double roll size and coverage)
- DecoratorsBest: Wallpaper glossary of terms (single and double rolls)