Wallpaper query

[ATOB2]

I know that there is a pretty safe way for knowing how many rolls of wallpaper you'll need to paper room. Does anyone know this equation?

[JohnThorn]

A standards roll of paper is 33 feet long by 21 inches wide. For most rooms, that means you can cut four lengths from each roll (unless it has a big pattern to be matched). So measure the perimeter of the room (i.e add up the lengths of all walls) divide by seven amd round up. So a 10 by 12 foot room has a perimeter of 10+10+12+12=44 feet so needs seven rolls.