Wallpaper Roll Calculation and Pattern Repeat Accurate wallpaper roll calculation is crucial when working with pattern repeat wallpaper to prevent running out of material. The pattern repeat size directly affects how much wallpaper is needed. Offset wallpaper and half-drop match wallpaper require additional rolls due to the staggered pattern alignment. To calculate wallpaper quantity... https://www.arthouse.com/blogs/how-to/pattern-repeat-pattern-match-the-low-down