We all know that in the last year the screens of mobile phones have grown significantly and from the 3.5 inches of the iPhone 2G it has reached 5.3 inches as the screen of the Samsung Galaxy Note terminal. Although Samsung exaggerated the Note, most smartphones have screens between 4-4.3 inches and many of them are not that comfortable in anyone's hand. Now you are probably wondering what exactly determined the manufacturers of Android terminals to increase the displays and implicitly the dimensions of the smartphones. Well the Retina Display seems to be the main reason why Android terminals have such large screens, but below I will present two theories.
Android OEMs and Google responded to the 3.5-inch 960×640 Retina display by improving the pixel format to 1280×720. But because Android renders text and graphics like desktop OSes (eg Windows, OS X) increasing resolution above 320 ppi means smaller UI elements. The display had to grow in size to compensate for shrinking UI elements. iOS renders the Retina display not by shrinking UI elements by one fourth but by doubling clarity and sharpness. Unless Google adds an additional "DPI level" beyond XHDPI, Android smartphones that match or beat the iPhone 4/4S in resolution will always be bigger, much bigger.
The first of them has in the foreground the Retina Display implemented in iPhone 4 and iPhone 4S, a screen with a resolution of 960 x 640 pixels and a density of pixels per inch of 321. Basically, the problem appeared in the density of pixels per inch in the case of Android, because an increase in pixel density on 3.5/3.7 or 4 inch screens would have resulted in a significant reduction of interface elements. To solve this problem, the screens had to be built in a larger format and together with them the resolution also increased, thus obtaining a satisfactory number of pixels per inch and close to that of the Retina Display. The measure has the effect of the giants in the picture above and not everyone is satisfied with the terminals as soon as they start using them day by day.
The second theory has in the foreground the implementation of support for LTE networks, more precisely the components necessary for the terminals to work on these networks have imposed an increase in the dimensions of the case and implicitly in the size of the screen. In addition to LTE components that are larger, the fact that LTE terminals need more energy should be taken into account, so larger batteries are implemented in devices and both arguments could be supported to explain why smartphones have larger screens 4 inch large.
Either of the two explanations has its point, now it depends on what applies to each individual Android smartphone.
