These calculations are based on the resolution (dots per inch, or DPI) of the image you provide. Uploading a higher resolution image means a larger image will look better at a closer distance. More technically, our system first examines the DPI of the image you upload. Then, based on that DPI, some mathematical formulas and our own experience, it inserts the image into your sign at the maximum size that will likely give you a clean, high-quality image when viewed at a distance of several feet. The system must assume that the image you provide 'looks good' to start with, as the only factor used when calculating the recommended physical size is the actual resolution (DPI) of the image you provide.