Calculator
Wallpaper Calculator: How Many Rolls?
Enter wall size, roll size and pattern repeat to see how many strips and rolls of wallpaper you need, calculated strip by strip. Doors and windows are deducted.
Wall dimensions
The repeat is the length after which the pattern repeats itself; it is printed on the roll label in cm. With a straight match every strip starts at the same point of the pattern; with an offset match the next strip drops by half a repeat. For plain paper choose “Free match”.
The offcut at the end of each roll is already in the calculation; this allowance only covers miscuts, corner overlaps and damaged strips. It is added to the strip count.
Result
9 rolls
The roll count comes from the strip method: each roll leaves an offcut too short for another strip, which dividing by m² cannot see. Buy all rolls with the same batch (lot) number.
Assumptions behind the calculation
- Strip length = wall height + trim allowance. The default trim allowance is 10 cm (typically 5 cm at the top and 5 cm at the bottom).
- On patterned paper the strip length is rounded up to a multiple of the repeat; with an offset match half a repeat is added first (the common half-repeat offset is assumed).
- A door is taken as 0.90 m wide. Only the strips that fit entirely inside an opening are deducted; the short pieces above doors and above and below windows are assumed to come from roll offcuts.
- The piece discarded at the start of a roll to line up the pattern is not calculated separately; the waste allowance covers losses of this kind.
- Paste quantity is not calculated: it depends on the paper type and the product, so check the consumption on the manufacturer's label.
The three most common mistakes when buying wallpaper
With wallpaper, running short means you may never find the same batch number again. Work it out in strips, not square metres.
Calculating by square metre
Dividing the wall area by the roll's m² ignores the offcut left at the end of the roll. A 10.05 m roll gives three 2.70 m strips and leaves 1.95 m, which is not enough for another strip. In a 4 × 5 m room with 2.60 m walls, m² division says 9 rolls; the strip method says 12.
Skipping the pattern allowance
On patterned paper every strip gets longer so it can pick up its neighbour's pattern: the strip length is rounded up to a multiple of the repeat. On a 2.80 m wall with a 64 cm offset repeat the strip grows to 3.84 m and a roll yields 2 strips instead of 3, so you need almost one and a half times as many rolls.
Mixing batch numbers
Rolls can differ in shade from one production batch to another, so the batch (lot) number on the label must match. A roll bought later to make up a shortfall can look different on the wall even if it is the same product. That is why it pays to buy in one go, with a spare roll if needed.
STRIP LENGTH = HEIGHT + TRIM (+ HALF A REPEAT for offset match) → rounded up to a multiple of the repeat
STRIPS PER ROLL = ROLL LENGTH ÷ STRIP LENGTH (rounded down, offcut not counted)
STRIPS = WALL WIDTH ÷ ROLL WIDTH (rounded up) − STRIPS THAT FIT INSIDE OPENINGS
ROLLS = STRIPS × (1 + WASTE) ÷ STRIPS PER ROLL (rounded up)
How many rolls of wallpaper do I need?
Wallpaper is calculated in strips. First find the length of one strip: add a trim allowance (typically 10 cm) to the wall height, plus a pattern allowance on patterned paper. Divide the roll length by the strip length and round down; that is the number of full strips per roll. Divide the total width of the walls by the roll width and round up to get the strips needed. Rolls = strips needed ÷ strips per roll, rounded up. Example: a 4 × 5 m room (18 m perimeter), 2.60 m high, plain 0.53 × 10.05 m rolls → 34 strips, 3 strips per roll, 12 rolls.
How many m² does one roll of wallpaper cover?
The standard roll common in Europe is 0.53 × 10.05 m and covers about 5.33 m². A wide roll is 1.06 × 10.05 m (≈10.65 m²), and the wide, long roll often sold in Turkey is 1.06 × 15.6 m (≈16.5 m²). The exact size is always on the label. But this m² figure only describes the size of the roll; it cannot tell you on its own how many rolls you need, because the roll is cut into wall-height strips and the offcut at the end does not cover the wall.
Why can't wallpaper be calculated by square metre?
Because the roll is cut into full wall-height strips and leaves an offcut at the end that is too short for another strip. A 10.05 m roll gives three 2.70 m strips and leaves 1.95 m; that piece does not become a new strip. Dividing the area by the roll's m² counts this offcut as usable: in a 4 × 5 m room with 2.60 m walls, m² division gives 9 rolls, while the correct strip calculation gives 12. The difference means the paper runs out halfway along a wall.
How is the pattern allowance worked out for patterned wallpaper?
The repeat is the length after which the pattern repeats itself, printed on the label in cm. With a straight match every strip starts at the same point of the pattern; the strip length (height + trim) is rounded up to a multiple of the repeat. With an offset match the next strip picks up the pattern half a repeat lower, so half a repeat is added first and then rounded. Example: a 2.80 m wall, 10 cm trim and a 64 cm offset repeat give 3.22 m; rounded up to a multiple of 64 cm the strip becomes 3.84 m. A 10.05 m roll then yields 2 strips instead of 3.
Are doors and windows deducted when calculating wallpaper?
Partly. Not the whole opening, only the strips that fit entirely inside it are deducted, because the short pieces above a door and above and below a window still need paper. This tool takes a door as 0.90 m wide: with 53 cm rolls a door removes 1 strip, with 1.06 m wide rolls none at all. The short pieces are cut from roll offcuts; on paper with a large repeat the offcut may not match the pattern, so do not set the waste allowance to zero.
How much wallpaper paste do I need?
There is no single rule. The type and amount of paste depend on the paper type (paper, vinyl or non-woven) and on the product. The paste packaging states how many rolls or m² it covers, and the wallpaper label states which paste to use and whether it goes on the paper or on the wall. That is why this tool does not give a paste quantity; go by the consumption on the manufacturer's label.
This tool gives an estimate and does not replace a site survey. How straight the walls are, the number of corners, niches and columns, where the pattern starts on the roll and the installer's technique all change the real consumption.
Let's plan your wallpaper together
The right number of rolls is half the job; the other half is wall preparation, pattern matching and a clean installation. In our renovation and decoration projects we plan wall coverings together with the whole space. In Ankara we visit on site and give you a clear quote.
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