For a product line touted to be magical, groundbreaking, and intuitive, the iPhone never went past the 3.5-inch mark for its display ever since the original product was unveiled by the late Steve Jobs in 2007. Competing smartphones, such as the Samsung Galaxy S II, have gone past four inches to display more and more details. But, what has actually made Apple refrain from expanding its iPhone’s display (and possibly for its later iterations)? Being practical.

A smartphone, with all its multi-touch capability, is actually best used with just one thumb, with the remaining fingers securely grasping the back and your other hand conveniently busy elsewhere. For instance, the most common smartphone tasks–making a call after selecting a contact in the phonebook, typing down a text message reply, and browsing the Web–typically only require single swipes and single taps. And, that should be done with your thumb alone.

But, try performing those tasks with phones whose display measures at least 4 inches diagonally. While you can comfortably tap away within the range of your thumb’s reach, there will certainly be remote buttons and whatnot that will have you fidget with your hand–which risks your phone’s falling to the ground. You have no choice but to use your other hand instead. That is what makes large screens ultimately useless, as shown in the image by Calling All Geeks.

The only other cases, where interaction with the device requires using multiple fingers simultaneously, are when playing games and watching movies. And, during these times, you usually hold your phone sideways (landscape mode) and possibly with both your hands.

The iPhone and its display size is the prime example of Steve Job’s demand for perfection. He himself may have noticed this flaw of some parts of larger screens becoming useless or void of interaction when using just one hand alone. You can try it for yourself and see how everything displayed in the iPhone can be reached easily, whereas you’ll be having a hard time on larger devices.

Furthermore, many smartphones have become so large that they are rather hard to hold, with their areas surpassing that of the average palm, and that your fingers can’t reach even the other side of the phone anymore. As a result, handling them with a firm, secure grip is no longer applicable, thereby increasing the likelihood of accidental drops.

Another reason I can think of is the fact that fashion these days demands tight or skinny jeans. Imagine how unsightly it would be if you put a large smartphone in your pocket, bulging at a disturbing level. In fact, would it have fit in your pocket comfortably in the first place? Had you carried a smaller device like the iPhone 4S, this won’t have to be a problem.

If the iPhone 5 (or whatever Apple decides to name its next phone) ever comes out with a larger screen, Apple may have already done something to address these problem. Perhaps they will have sported it with a flexible LCD display. But, for now, be thankful that your iPhone 4S’s screen is smaller.

However, the larger screen on Android phones also have a practical reason–bigger viewing space.  Since smartphones these days are already hooked up to high-speed data networks, the Web is readily accessible from smartphone users’ devices.  The larger screens on recent Android devices, although arguably not as one-thumb-friendly as a 3.5-inch form factor, also provide a bigger window for more content to be shown on the display.  That is as much practicality as limiting the screen size to just 3.5 inches for the sake of thumb reach.  It also allows for less scrolling (with the thumb) when viewing content.

Do you find the 4.3-, 4.5-, or 4.65-inch touchscreen on your Android phone woeful to your thumb?  Or do you find it acceptable enough for one-hand use?

Conan Hughes
Contributor at Android Authority covering all things Android.