CALCULATE THE NUMBER OF ROLLS OF WALLPAPER

As a general rule a standard roll of wallpaper measures 0.53m wide and 10.05m long.
Here is how to calculate the number of rolls you need:

1. First, you need to calculate the perimeter of the room to be papered, not including the openings (doors and windows). You also need to work out the height of the wall and factor in an extra 10cm to trim every strip.

2. Once you have calculated the perimeter, you can work out the number of strips you need. To do this, divide the perimeter by the width of a strip (0.53m). Only count in whole numbers. Round up to the next whole number if there is a decimal remaining.

3. Next, take the length of the rolls (10 meters) and divide by the height (don’t forget to add 10cm). Finally, to calculate the number of rolls of wallpaper you need, take the number of strips and divide by the number of strips in a roll.

Wallpaper without matches
1. Calculating the perimeter
P = Perimeter
P = (A + B) x 2 – (Width of doors and windows)
2. Calculating the number of rolls needed
P/0.53 = x: No. of strips needed
3. Number of rolls needed
10.05/h (height) = y: no. of strips in a roll
x/y = No. of rolls needed

For example:
for a room with two 3.50m walls and two 4.10m walls, a height of 2.95m, a 0.80m door and a 1.25m window.
Perimeter measurement: (3.50+4.10) x 2 = 15.20 meters
Deduct the openings: 15.20m – (0.80+1.25) = 13.15 meters
Number of strips needed: 13.15m divided by 0.53 = 25 strips
Height of every strip of wallpaper: 2.95m + 0.10m = 3.05 meters
Number of strips in a roll: 10 divided by 3.05 = 3
Number of rolls needed: 25/3 = 8.33 rounded up to 9 rolls.
If there are any alcoves, add 1 to 2 extra rolls.

Calculating the number of rolls when the wallpaper has a straight match or a drop match:

Paper with a straight match P = (A + B) x 2
p/0.53 = x: no. of strips needed
10.05/ (h + match) = y: No. of possible strips in a roll
So x/y = no. of rolls needed

Paper with a drop match P = (A + B) x 2
P/0.53 = x: no. of strips needed
10.05/ (h + match) = y: No. of possible strips in a roll
2
So x/y = no. of rolls needed

Modern wallpapers are 10.05m long, 53cm wide and have a 53cm match (the pattern repeats every 53cm).
Simply imagine that you’re hanging 53cm x 53cm tiles!
In this case you should count the number of tiles you will need to use using the following calculations:
Anything cut from a tile will not be used.
In a 10.05m roll, there are 18 whole 53cm tiles.
         For a 2.50m high wall, you need 2.5/0.53 = 4.7 tiles (5 tiles).
A 10.05m roll therefore contains 18/5 = 3.6 strips (or only 3 if you are not matching horizontally).

No horizontal match 

With horizontal match

For example:

Take a room with a perimeter of 15m which we want to hang with wallpaper, matching horizontally:
The number of strips is 15m/0.53m (width of a strip) = 29 strips.
The number of tiles is 29 (strips) x 5 (tiles per strip) = 145 tiles
As there are 18 tiles per roll, we need 145/18 rolls, rounded up to the next whole number = 9 rolls.