So what is about those Android screen sizes?
Android is a platform that gives mobile device manufacturers great freedom in terms of creating devices. Starting with subassemblies such as a battery, CPU, and memory, through all types of sensors up to screens, which plurality of resolution, size, and density can sometimes be – to put it mildly – pretty overwhelming. Fortunately, Android creators came up with a set of baskets that group devices concerning their density. This subtle touch unburdens software developers from adjusting applications to all kinds of Android screen resolutions.
As a result, we are offered 6 such consecutive baskets: ldpi, mdpi, hdpi, xhdpi, xxhdpi and xxxhdpi (we can also distinguish tvpdi that can be placed between mdpi and hdpi, but due to its proximity to the two, we won’t discuss it here). Of course, we should not equate density baskets with the physical size of the device. You might wonder then: so what is this magical density about? It is the number of pixels that can fit on a physical area of the screen, often described as dpi (dots per inch).
What are the densities?
These densities are primarily working tools for designers and graphic artists. That's why they should deliver the graphics prepared for the particular density baskets. Developers can also use them in their applications to create, for example, different layouts depending on the density of devices. However, it is often more useful to utilise the smallest edge of the device expressed in dp units (swdp from the smallest width), the orientation of the device (land and port), and sporadically predefined sizes such as small, normal, large and xlarge. What is interesting, in the same way, you can use different resources, depending on the API version for example, and mix them with one another! A few years back, Android operated only one set of the first four density baskets.
From ldpi to xxxhdpi
Since the rapid development of mobile devices and moving away from their miniaturization, it is very rare to encounter devices with screens with ldpi density. The vast majority of today’s flagship models (often due to the size classified already as phablets) works on xxxhdpi. Nexus 6, Nexus 6P, Galaxy S6, S7 Galaxy, LG G5 are examples of such. Thus, it is worth to forsake the preparation of graphics for the smallest density, at the expense of preparing the version for the two largest ones. This results in the visual quality being at the highest level.
At this point, it is worth to touch upon the system of units, which should be used by Android developers so that view components look the same on all devices. And so, for the font sizes, it is recommended to use the sp unit (scale-independent pixel), while for all other dimensions – the dp (or dip) unit (density-independent pixel). Base density for Android is mdpi. All other densities are its appropriate ratios, which is as follows:
- 0.75x – low-density (ldpi)
- 1.0x – medium-density (mdpi)
- 1.5x – high-density (hdpi)
- 2.0x – extra-high-density (xdpi)
- 3.0x – extra-extra-high-density (xxhdpi)
- 4.0x – extra-extra-extra-high-density (xxxhdpi)
Android screen resolutions fall into certain ranges, which are represented by baskets:
- ldpi – ~120dpi
- mdpi – ~160dpi
- hdpi – ~240dpi
- xhdpi – ~320dpi
- xxhdpi – ~480dpi
- xxxhdpi – ~640dpi
Few words about the devices
In terms of support for different screen densities, for which customers sometimes ask, we should pay attention to a much more significant issue which is a supported version of Android. The whole framework is developing rapidly, virtually in every way (code, appearance, behaviour). This often arises problems with creating solutions that are available in new versions, but they are not, or are in a very limited way available on older versions. Currently, support for Android in versions 2, 3 and first editions of the version 4 is already not much reasonable.