Our Wallpaper Calculator will estimate the number of wallpaper rolls you need for the space you are looking to decorate. Please, can you double check that you are entering the correct measurements into the calculator. You will see that our website will automatically fill in the wallpaper's Roll Width, Roll Length and Roll Repeat. All you need to do is enter the measurements of your wall - Wall Length and Wall Height (in meters.) We regularly test our Wallpaper Calculator and very rarely experience technical faults.