I had design ad iPhone application for our company and working with iPhone screen and resolution was a key aspect in this design process. The actual pixels are different in different iPhone models, which will effect the appearance of graphics and interface for iPhone applications. Defiantly knowing about resolution and PPI should not be limited to designers, it actually effects the picture quality and graphic of any user experience with the device. Here are the Screen resolution and PPI detail of different iPhone screens. iPhone 4 and iPhone 4 has Retina Display devices which have more HD graphics.

. iPhone 5 Screen Resolution and pixels per Inch
* iPhone 5 has 640×1136 screen resolution which 3x larger then the non- retina and old phones.
** iPhone 5 has a much higher pixel density than it’s predecessors not including iPhone 4 its displaying resolution is 326ppi (pixels per inch).

iphone5

. iPhone 4 Screen Resolution and pixels per Inch
* iPhone 4 has 480×640 screen resolution which 2x larger then the non- retina and old phones.
** iPhone 4 also has a higher pixel density than it’s predecessors, its displaying resolution is 326ppi (pixels per inch).

iphone4

. iPhone 2g, iPhone 3G & 3gs Screen Resolution and pixels per Inch
* iPhone 2g, iPhone 3 and iPhone 3gs have 320×480 screen resolution which are non- retina display devices.
**iPhone 2g, iPhone 3 and iPhone 3gs have only 163ppi (pixels per inch) Screen resolution.

iphone-3gs

Here is the little compression of retina and non- retina screen display devices

iphone-4-screen-comparison