Firstly measure your wall. Lets use an example here of 4.2 wide by 2.5 high
Check the product description for the roll size: For example 53cm x 10m
On our 2.5 height wall you will get 4 drops of wallpaper from this roll – 10 divided by 2.5 = 4
Now divide the width of the wall ( 4.2 ) by the roll width of 53cm = 7.92
This means you need 8 drops.
If there is a pattern repeat this needs to be calculated too.
So if the pattern repeat is 53cm you need to add that on to the wall height – 2.5 + 0.53 = 3 m. This tells us that you will now only get 3 drops from the roll.
So 8 drops divided by 3 lengths = 2.66 So rounded up to you needing to order 3 rolls