Estimate the number of wallpaper rolls you will need to cover a wall using Imperial measurements.
Wallpaper comes in a variety of widths and lengths.
European/Metric 20 1/2 inch. American rolls 27 inches. Commercial wallpaper is available in various widths 36", 48", 54" and 60".
Check the specifications of the wallpaper you are planning to use. It should tell you the roll width, length and the pattern (design) repeat. These, plus wall length and height are the values you will need to calculate the number of rolls you need to cover your wall.
The pattern repeat will calculate the usable amount of your roll of wallpaper. It will deduct a certain amount of waste you will get for having to match the design of your wallpaper for each drop. Adding a certain amount in addition to this for waste is not a bad idea. Having an extra roll of wallpaper will make your life much easier.
For wall openings such as windows and doors, ignore smaller sizes and calculate the total square footage of all openings combined that you wish to deduct from the area you are covering in wallpaper.