The screen size isnt always indicative of the full size of the phone. Bezelsthe four sides of the frame around the screenare usually not accounted for and can make a big difference in the size of the phone you get, even if the screen size is the same.
For example, take the Sony Xperia Z1 Compact, the Samsung Galaxy S4 Mini and the HTC One Mini. All three of them have 4.3-inch screens. But the difference in length
The HTC One Mini, although the same screen size as the S4 Mini, is 7.5 mm more in overall length. In case you were wondering, the math stands at:
2.5mm = 0.1 inch
The HTC One Minis length, of course, is bolstered by the front-facing stereo speakers it packs. But if you were to go by the Mini aspect of it alone and think thats the best screen you can get in that size of phone, youre mistaken. Here are three more phones around the same length but with different screen sizes:
And if you think this phenomenon is symptomatic of smaller screens, youre mistaken. Take a look at some of last years flagship models:
Why overall length matters
With the above chart, its clear that if you were choosing between the HTC One and the LG G2, youd get half an inch of extra screen space for an additional millimeter of overall length. Between the Sony Xperia Z1 Compact and the Samsung Galaxy S4 Mini, the latter has smaller bezels and yet makes better use of them by including physical and capacitive buttons on the bottom bezelthe Z1 Compacts 4.3-inch screen loses further space because of the virtual on-screen buttons.
When youre buying a phone, you want the largest possible touchscreen in it. So when you think a particular size is right for you, make sure you are looking at overall length and then judging the largest screen you can get in itdont just go by screen size.