What is the Wallpaper Roll Calculator?
The Wallpaper Calculator is an interior design tool that ensures you order the exact right amount of expensive wallpaper. It factors in the complex "pattern repeat" waste, preventing the nightmare of running out of paper halfway down a wall.
How to Calculate Wallpaper Rolls and Pattern Match (Formulas)
Wallpaper requires significantly more mathematical waste than paint because the printed pattern must align perfectly at every seam.
- Usable Strip Length: Your wall's height, mathematically rounded up to the nearest full increment of the Pattern Repeat. If there is no pattern, it simply adds 4 inches for trimming waste at the baseboards.
- Total Strips Needed: Room Perimeter / Width of the wallpaper roll.
- Strips per Roll: Total length of the roll / Usable Strip Length.
- Rolls Required: Total Strips Needed / Strips per Roll (Rounded up).
Frequently Asked Questions
What is a Pattern Repeat (or Pattern Match)?
The pattern repeat is the vertical distance (e.g., 24 inches) before the floral design or geometric shape starts over again. When you hang the second strip of paper, you must slide it up or down so the flowers align perfectly with the first strip. This forces you to chop off and throw away large sections of blank paper at the top, creating massive waste.
Why should I never subtract windows and doors?
Unlike painting where you subtract the square footage of a window, wallpapering requires full, continuous vertical strips to maintain the pattern match across the wall. You must hang a full strip right over the window and then cut out the hole with a razor blade. You must calculate as if the wall is completely solid.
What are dye lots and why do they matter?
Wallpaper ink is mixed in massive vats. If you buy 3 rolls from "Batch A" and run out, buying 1 more roll from "Batch B" is highly risky. The ink color in Batch B will likely be a slightly different shade of blue. When placed side-by-side on the wall, the seam will be glaringly obvious. Always order 1 extra roll from the exact same dye lot upfront.