Buying the rolls: Wallpaper usually is sold in double or triple rolls, which is confusing since it's priced by the single roll.
Example, if a single roll, which covers about 25 square feet, is priced at $10, but packaged as a double roll, it will cost $20.

Generally, calculate the square footage of walls by multiplying the wall height by the distance around the room (perimeter).
Example: A 10-by-12-foot room (perimeter equals 44 feet) with an 8-foot-high ceiling would have 352 square feet of wall (multiply the perimeter, 44, by 8, the ceiling height). Divide total square footage by 25 (the amount of wall coverage per single roll) for the number of single rolls needed, which is about 14.
Deduct a single roll for each doorway and a half roll for an average-sized window.

Pattern repeat: This refers to the size of the pattern that has to be matched to each panel of paper, and can affect how much wallpaper will be needed.

The types of repeats are:
Straight Match: Every strip should be the same at the ceiling line, the pattern matches straight horizontally.

Drop Match/ Half Drop Match: Every other strip will be the same at the ceiling line. The pattern drops down on the paper every time it is repeated.

Random Match: The pattern matches no matter how the adjoining strips are positioned. Examples are grasscloth and just random images.
A large pattern drop means more waste on each roll. If you choose a pattern with a large 12" or more repeat simply add the amount of the repeat,say 12" to the ceiling height when calculating how much you need and that will allow for the extra waste. If the ceiling height in your room is 8' simply consider it to be 9'.

Here is a real handy Wallpaper Calculator

Wallpaper stores and some home-improvement centers offer free wallpaper classes and how-to brochures.

Where to Next?
Use the Wallpaper Menu at the top left or below to the Site Menu