You can also go under your mouse settings. dpi resolution dpi dpi Pixel mm dpi calculate calculate calculate DPI Calculator - Result Total Pixels x Pixels Mpx Photo/Image/Picture Size x mm. The following formula gives the number of pixels, horizontally or vertically, given the physical size of a format and the pixels per inch of the output: There is a button on the mouse, you can change your DPI for your mouse from the button quickly. Since most digital hardware devices use dots or pixels, the size of the media (in inches) and the number of pixels (or dots) are directly related by the 'pixels per inch'. 4.2 Calculating PPI of camera view screens.