Have you ever noticed that everything looks larger on Android smartphones than on iPhone in the same apps? And the fact that everything looks larger on a phablet than on a compact smartphone, and as a result there is exactly the same amount of information on the screen?
What's wrong with pixel density
Everything is just like that. But what is the reason for this? Android supports screens with different pixel densities. Not all of them were originally. But by the current moment there are five standard values: 160, 240, 320, 480 and 640 dpi. They are standard because they represent all the application's raster graphic resources (pictures). There are also non-standard pixel densities, but more on them later.
If you take the most typical devices for today – 5 ″ HD and 5.5 ″ FHD, it turns out that their pixel densities are 294 and 400 dpi, respectively. What happens in this case? The physical and software pixel density is different. When an application asks the device: 'What is your pixel density?', It always receives only the standard value in response. Of course, no one bothers to write an application for a specific phone model and take into account the discrepancies, but application programmers do not do this. Such a subtle adaptation can only remain in the shells of vendors that make the smartphone itself.
If the physical and software pixel densities are different, in which direction? Let's take an example. The height of a standard Material Design button is 0.225 inches (5.715 mm). If a device with a physical dpi of 400 declares a software dpi of 320, then Android will draw a button with a height of 3200.225 = 72 pixels. And on a physical screen, it will take 72/400 = 0.18 inches (4.572 mm). And this button will be more difficult to hit with your finger. Therefore, manufacturers tend to specify software pixel density higher than physical. Those. for 400 dpi physical it will be 480 software. Exceptions are only in cases where the deviation is only a few percent. For example, smartphones with a physical pixel density of 342 dpi report a software 320.
We calculate the real dimensions
Now let's take a closer look at the calculations that we just made. They are based on the fact that resolution, pixel density, and size are all interdependent. And knowing two of them, the third can be calculated. Let's do it for the screen size. For example, let's take a smartphone with a resolution of 1080 × 1920 (FHD) and a pixel density of 400 dpi. Such a screen will have a size of 2.7 x 4.8 inches. By the Pythagorean theorem, you can calculate the diagonal. It will be approximately 5.507 inches. But, as we already found out, the software pixel density is not 400, but 480 dpi. Therefore, from the point of view of application software, the screen will be 2.25 “x 4”, which gives a diagonal of only 4.6 “! And if we take a smartphone with a resolution of 720 × 1280 (HD) and a software pixel density of 320 (against a physical 342), we get exactly the same software size – 2.25 × 4 inches (and exactly the same diagonal of 4.6 inches). Those. devices differing in diagonal by 1.2 inches (which is quite a lot in such sizes) look exactly the same from the point of view of application software and they hold the same amount of information. It's just that on a larger smartphone, everything looks larger, but that's all. We will illustrate this with screenshots of the My Shows application from smartphones Xiaomi Mi 2s and Samsung Galaxy Note 3.
The software size of smartphones is the same and we see that both fit only six full lines from the list of TV shows and part of the seventh line (all seven if you turn off ads). So the Galaxy Note's large size doesn't give us any advantage – we can't see more information on its screen.
Here we should make a very important digression and say that in applications with large amounts of text (browsers, book readers) we can flexibly adjust the font size and thus get completely different amount of information on different screens. In this case, the big screen will have a clear advantage.
What screens can be
Since non-standard resolutions are practically not used in Android (and if they are, they are based on standard ones, just one side is slightly longer), then we can calculate in advance all possible software sizes of smartphone screens:
|
Resolution \ dpi |
160 |
240 |
320 |
480 |
640 |
|---|---|---|---|---|---|
| 480 × 800 (WVGA) |
5.83 ″ |
3.88 ″ |
– |
– |
– |
| 540 × 960 (qHD) |
6.88 “(3.375 × 6”) |
4.6 ″ |
3.44 ″ |
– |
– |
| 720 × 1280 (HD) |
– |
6.12 ″ |
4.6 ″ |
– |
– |
| 1080 × 1920 (FHD) |
– |
– |
6.88 “(3.375 × 6”) |
4.6 ″ |
3.44 ″ |
| 1440 × 2560 (QHD) |
– |
– |
– |
6.12 ″ |
4.6 ″ |
As you can see, for almost the entire variety of smartphones with different resolutions and different diagonals, we most often run into the same software size – 4.6 ″.
New heroes
The situation could look downright depressing. Especially against the backdrop of the appearance of iPhone 6 Plus – a real phablet with a large not only physical, but also software diagonal. But it turns out that everything is not so bad. In recent years, smartphones with non-standard pixel densities have appeared. Take the Nexus family for example:
- Nexus 5x – 420 dpi;
- Nexus 6 and 6p – 560 dpi.
Samsung is starting to use the new densities with the Galaxy Note 5 (the Note 4 and S6 had 640 dpi soft density).
Moreover, in Android 7 there was an open (in Adroid 6 there was a hidden) ability to change the pixel density. For example, on a Nexus 5x, changing the setting produces the following dpi values: 356, 420 (default), 460, 500, and 540.
If you have a smartphone with an old version Android, then you can try changing the /system/build.prop file. Attention! This can lead to 'oskirpichivaniya' the device !!! Especially if you set a non-standard pixel density. The parameter in the file is named 'ro.sf.lcd_density'.
Let's try to calculate the possible software sizes of smartphones for non-standard pixel densities (with default settings):
|
Resolution \ dpi |
420 |
560 |
| 720 × 1280 (HD) |
3.49 “(1.71 × 3”) |
— |
| 1080 × 1920 (FHD) |
5.25 “(2.57 x 4.57”) |
3.93 “(1.93 x 3.43”) |
| 1440 × 2560 (QHD) |
7 ″ (3.41 × 6.1 ″) |
5.25 “(2.57 x 4.57”) |
As you can see, the new popular software screen diagonal is 5.25 ″.
Is the non-standard pixel density fraught with something in new devices? Some applications may not adapt to it and may render their interface incorrectly. There is also a nuance that the raster graphics will be taken from a 'foreign' resolution and scaled to the desired one.
And if you just change the font size?
How does the ability to change font size relate to all complex experiences? After all, you can simply make it smaller and then more information will appear on the screen. So? Not really. As mentioned above, if the application displays a large amount of text (reader or browser), then this technique works fine. However, in line-of-business applications, developers can specify the physical size of elements regardless of the font size. Let's try to check how the My Shows application behaves on the same phone with different font sizes:
On the two screens shown, the font size differs by 3 stops (-1 and +2 to standard). And this example is far from unique: both app customers and their developers do not always try to optimize an application for different font sizes.
How to find out the software size of your smartphone
Before moving on to determining the size of a smartphone and comparing the sizes of different devices, you should clarify the units of measurement. Nobody uses inches to work with dimensions – when working with them, fractional numbers are obtained and you must constantly apply correct rounding. In order to work only with integers, Google uses the concept of 'density-independent pixels' (dp or dip for short). One dp corresponds to:
- 1 pixel at 160 dpi;
- 1.5 pixels at 240 dpi;
- 2 pixels at 320 dpi;
- 3 pixels at 480 dpi;
- 4 pixels at 640 dpi
For 420 and 560, the numbers are 2.625 and 3.5, respectively.
The most popular software size of 4.6 ″ smartphones is 360×640 dp. 5.25 ″ is already 411×731 dp. In order to find out the size of your smartphone, just run the Screen Info utility or the like. Below are examples of screenshots of this utility for Xiaomi Mi 2s, Samsung Galaxy Note 3, as well as LG Nexus 5x with all possible dpi values set in the display settings. Please note that for devices with on-screen buttons, the utility shows the size of only the free area of the screen, excluding buttons (when you press the top button in the interface, the full size will open).
Conclusion
So, let's summarize. Does a large physical screen always mean that more useful information will be displayed on the screen? No. It is guaranteed to be larger only for a solid “sheet” of text with flexible adjustment of the font size. In business applications, screens with different physical sizes can include the same amount of information. But the situation does not stand still and there are, if not gigantic, but at least some progress.