How Does Screen Size Affect Data Use? March 2013

When people debate which smartphone to buy, the conversation quickly becomes more complex than simply iOS or Android. The operating system, while important, is only one factor among several. For many, the most important hardware characteristic of their prospective phone is screen size, with many users (I'm looking at you Galaxy Note fans) arguing that bigger is always better. As the Galaxy S4 has recently launched with a bigger-than-expected 5-inch diagonal screen, we decided we'd take a look and see how much screen size affects how people use their phone. While we have explored Android fragmentation before we have never previously looked at how that fragmentation actually affects user behaviour.

In order to look at this we compared the amount of data used on devices of various screen sizes, with a few conditions to ensure that the data we were getting was representative. All data is collected from users of our Android app, which is why the devices plotted are all Android-powered. While this may seem like a limitation, the vast fragmentation of Android devices gave us a very broad scope for examining the impact of screen size on user behaviour. In order to be included the individual device-user had to have accessed both cellular and Wi-Fi data on the same day. For similar reasons we restricted our data to areas with a high level of Wi-Fi penetration in order to ensure that users had both available to them in order to make a fair comparison.

Screen Size vs Data Use Over a Cellular Connection


Each additional square inch of screen area leads
to 75MB of extra data downloaded per month over a cellular connection

As can be seen there is only a weak correlation (with a Pearson co-efficient of 0.21) between screen size and data use over a cellular connection. What this suggests it that people broadly use their cell phones in the same way when on the move, as there is only a weak relationship between screen size and increased data use. The significance of this is demonstrated through comparison with the graph below.

Screen Size vs Data Use Over a Wi-Fi Connection


Each additional square inch of screen area leads
to 288MB of extra data downloaded per month over Wi-Fi

As can be seen there is a significant correlation (with a Pearson co-efficient of 0.55) between screen size and data use over Wi-Fi. As screen sizes get bigger, people consume considerably more data. For example, data use over Wi-Fi doubles from a device with a 6 sq inch screen (like a Galaxy Ace) to a device with a 9 sq inch screen (like a Galaxy SIII).

Concluding Thoughts


What these two sets of data show us is that screen size strongly affects data consumption over Wi-Fi. In comparison, screen size has a much weaker impact on data use over a cellular connection. Our best hypothesis for this is the case is that places with Wi-Fi are often those where the user has more choice in how to access the Internet. For example, they may have access to a PC or Internet TV and in these cases it appears to be screen size that is the defining factor in whether they choose to remain mobile. On the flip side to this, our data suggests that, when on the move, people treat their mobile devices in much the same way, consuming approximately the same amount of data. When on the go, people use their cell phone for their immediate needs and there is no trade-off in utility based on screen size because of the lack of alternative options to trade off to. What our results show is that screen size plays a big role in determining how people use their phones to consume Wi-Fi data. The consumption of cellular data, on the other hand, appears to be much more driven by factors that are unrelated to the phone's hardware.

Further Notes:

In total, data from 9,962 distinct devices was used in compiling this report.

We removed the top 2% of data users over Wi-Fi and cellular in order to minimize the effect of a few users warping the dataset with non-typical behaviour.

Screen area was calculated by taking the number of pixels and then dividing by the square pixel density in PPI.

All selected devices are from countries with a high level of Wi-Fi penetration, for more details download the pdf version.

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