You have to decide on the aspect ratio when chosing a digital photo frame, there are 4:3 and 16:9 available in the market. For example, if you buy a 7" 16 by 9 photo frame, and most of the photos are either 3:2 or 4:3, you will end up using only the middle portion of the display, that will be equivalent to a 5" 4:3 display.