Megapixel Calculator is very useful and informative app for understanding different resolutions. Just type number of megapixels and you will see all possible variations of screen, photo and camera resolutions. Or even more - type the resolution of your photo, screen or camera, and the app will tell you the aspect ratio and number of megapixels. Now app includes DPI calculator. Just input screen resolution and size in inches, and the DPI of the screen will be shown.