Since wallpaper color can vary from print run to print run, you should buy all the wallpaper you need at one time. To determine how many rolls a room will need:
- Add together the width of walls in feet, and multiply by height.
- Divide that by 30 — the average usable square feet in an American-made roll — or by 25, if you are using a European-made paper.
- Subtract a half roll for each normal-sized window and door.
You now have a working total; add one roll for good measure (and future patches) — a little more if your pattern has large repeats to match.
If you are uncertain of your calculations, draw a picture of each wall, including measurements and the position and size of all the windows and doors. Take the sketch to your wallpaper supplier. An experienced salesperson can offer advice on how many rolls you need to purchase.
When you place your wallpaper order, also buy compatible paste and a paste brush for standard papers, or a water box for prepasted papers.