How many wallpapers do you need for a room of 20 meters?
It is necessary to multiply the length of each wall by the height and subtract the area of the doors and window promos. So you will know the area of wallpaper. Then calculate the area of each tube of wallpaper (multiply the length by width), and then divide the area of wallpaper into the area of one tube. Get the required number of handsets. If the picture requires adjustment, then you need to take a little more wallpaper. Usually on the package they write the height of the rapport (repeating segment of the pattern).
It all depends on what kind of wallpaper you will glue, how wide the roll is, the meter is 60cm. It depends on what the height of the ceilings in your room. Not a few important factor is the pattern on the wallpaper, If you customize it, then the wallpaper will need more. You did not clarify all this and the answer, accordingly, will not be completely useful.
It depends on many factors, namely: the height of the ceilings, the geometry of the room (the more it is elongated, the greater the perimeter and wall area for the same area of the room itself), the number of windows and doors, the wallpaper design (whether it requires fitting or not) Whether the option of horizontal joints is acceptable or the sticker is principled only on one-piece strips, the width of the wallpaper (53 cm or meter).
If we take the middle version (ceiling 2,6 m, aspect ratio of the room 5,5 by 3,6 m, one door and one balcony block with one battery, wallpaper 53 cm wide without adjusting the pattern), then we get 4 stripes from one roll of wallpaper , or 2 running meters of the wall, the perimeter of the room is 18 m, minus 2,5 running meters on the door / window - 8 rolls come out, as they say, end-to-end, but 9 is better, so as not to guess "enough is not enough". In other layouts (for example, ceilings 4,2 and elongated geometry), the flow rate can be up to 2 times higher.