Adjusting Android Resolution, pixel density and font size for large print

The quick recommendation: What works best in one app, doesn’t necessarily work best in other apps, so the best solution is one which can be adjusted easily. Font size is easy to adjust and effective. Pixel density can also be effective in some cases.

The longer answer:

Recently I’ve tried rooting my phone and installing a custom ROM. More on that in another post shortly, but one of the big reasons I was keen to try this, is that it gives you access to settings you can’t otherwise touch and I wanted to see how I could manipulate these to increase the large print useability of my phone.

My previous post on DPI (Pixel density) and resolution on a Windows PC (here: has some explanation of the technicalities, which mostly translate across to a phone. On the PC I recommended setting he resolution to its highest, the DPI high and using the magnifier as needed beyond that, but I’ve never been a fan of using magnification on my phone if I could avoid it as the screen is so much smaller and more fiddly to pan around with my big fingers!


In my testing, I manipulated three settings

Resolution: This is how many pixels (dots) wide and high the screen is. On my Samsung galaxy note 2 for instance, it is 720 x 1280. Theoretically, lowering these numbers could make things appear larger as something which is 180 pixels wide will take up ¼ of the width of the screen at this resolution, but if I drop the resolution to 360 x 640 then that 180 pixel wide item is now half the width of the screen (that’s how it works on a Windows PC).

Pixel Density: (often used interchangeably with the terms Pixels Per Inch, PPI and Dots Per Inch, DPI) This is how many pixels are displayed in a line per inch of screen space – From a hardware perspective, the higher this number, the sharper and clearer the display looks. Adjusting this higher than the hardware specifications has the effect of enlarging things. If your phone has an actual hardware Pixel Density of 200 and you change the pixel density setting to 400, something which should be 1” high will be drawn 400 pixels high, but because your phone can actually only display 200 pixels to an inch, that object will render at 2” high.

Font size: I’ve covered apps which let you change font size before (here: ) and this time I’m looking at the effect that adjusting font size (along with resolution and pixel density) has on the useability of apps.

Testing methodology:

Currently, I have 200 apps on my phone, and even more conveniently, 100 of these could be considered to be ‘games’. I make the distinction because some will say they don’t play games, and I was also interested to see how differently games behaved to other apps. I tried using each app in six different scenarios:

  • Control: The native resolution (720 x 1280) and pixel density (320) of my phone at standard font size.
  • Most adjusted: A lower resolution of 450×800, higher pixel density of 400 and font size at 200%.
  • Slight tweaking: Native resolution, 150% pixel density (480) and 150% font size.
  • High DPI: Native resolution but double pixel density – 640 rather than 320, standard font size.
  • Lowest resolution: A resolution of 270 x 480 (pixel density scaled back accordingly to 120)
  • Large Font: Native resolution and pixel density but 200% font size.

The “most adjusted” setup was designed to affect the most parameters and so be more likely to have an effect (one way or the other). The “Slight tweaking” setup was designed to be a potentially practical solution which didn’t adjust any value too harshly, but provided a combination of effects which would hopefully be beneficial.

Effect of adjustments:

Resolution: Changing the resolution had the least effect in most cases. It turns out that most apps seem to be designed to draw things as a percentage of screen size so this didn’t make any difference to most things.

Pixel Density: Changing the pixel density tended to make things bigger, from the status bar to the size of icons and information within apps. Some apps handled this well and it was a great improvement and other apps, particularly some of the games, became unusable.

Font size: Changing the font size increased the size of text in many apps. Often this made the text easier to read, however in some cases the text was then bigger than the app was expecting and so overwrote other information or caused things to disappear off the side or bottom of the screen.

Some apps displayed exactly the same regardless of how I changed settings. In one way this was good as it meant that they were not negatively affected by any of the changes, but on the other hand it meant that I was not able to come up with a way of improving their large print readability beyond any settings in the app itself.

Just to take one marker, I’ve listed the size of app headings on their individual pages in the Play Store for each setting below:

  1. Control: 12pt
  2. Most Adjusted: 48pt
  3. Slight tweaking: 24pt
  4. Highest DPI: 22pt
  5. Lowest Resolution: 12pt
  6. Large Font 22pt

Usability results for (non-game) apps:

Leaving things untouched was the equal best case in 39% of apps and the equal worst setup in 89%. It was possible to adjust the pixel density, resolution or font size such that there was an improvement in 83% of apps, and in only 16% of apps, some combinations of changes caused a negative reaction.

The two biggest improvements here were in adjusting the font size (better in 71% of cases and worse in only 2%) and pixel density (better in 70% of cases and worse in 9%). While the slight tweaking scenario was only the best case in 3% of apps, this was mostly because there was an improvement (79% of apps) however it wasn’t as marked as when we doubled the DPI or font size. This setup was only worse than doing nothing in 6% of apps.

Adjusting the resolution had the least effect here – it was the same in 98% of cases (worse in one and better in one).

Results for games:

The default setup was the equal best setup in 78% of cases and the worst case in only 12%. Only 22% of games could be improved by adjusting the settings and 39% of games could be made worse or unusable with the wrong setup.

Similar to the non-game apps, lowering the resolution all the way down didn’t change anything for 93% of games though in 73% of cases this was still equal to the best setup. Adjusting the font size made 15% of games better and one worse and was the (equal) best setup in 77% of cases.

Changing the pixel density (and thus also the two combined scenarios) actually made things worse more often than better – not so much for font size alone, but just because some of games weren’t designed to cope with such an adjustment and only improved things for between 12 and 17 games but made things worse for between 14 and 35 games.

Overall results:


Above: The music Cyanogenmod music app, in the default resolution / pixel densit, in the most adjusted setup and in the slight tweaking setup.

Adjusting the pixel density seemed really good for many productivity based apps, but can be detrimental to some of the games. Adjusting the font size seemed overall to have the most positive effect with the fewest negative situations. In an ideal world, the best solution would be if there was a way of quickly changing the font size and pixel density for different situations.

Changing setups:

In my testing, I used an app called “Font Size Setter” by Cedric Gatay ( , to adjust the font size setting. I found this app good as the interface is basically just a slider you adjust to choose the size and an apply button which immediately makes the change. I also placed a shortcut to Font Size Setter in my notification shade using Custom Notifications, which made it even easier to bring up.

I used Resolution Changer by Lugalabs ( to adjust the DPI and resolution, and the way this worked was that after making the change, the screen would flicker, and then take you to the phone’s lock screen. During this time it also displayed a message asking if you wish to keep the changes and giving you 15 seconds to agree before going back to the old setting (similar to when you adjust the screen resolution on a Windows computer). While effective and potentially a safeguard in the event of choosing a setup your hardware could not display, I did find that this process took a little while, and I would be reluctant to want to change DPI too frequently. If there is another app which does the process more easily I would be very excited to learn of it.


With most of my previous recommendations, it’s been possible to choose one or several apps or setups which work best to achieve a particular outcome. With adjusting the display properties with the goal of making the font larger, there isn’t one recommendation which will work for everyone. Some apps respond great to some tweaks, whereas others become unusable, and depending on what apps you use, you will likely find that what works in one app, doesn’t work in another. For myself, I’m still using the slightly higher DPI mode though I tend to leave my font set at 200% except where this causes problems, but at least I can easily adjust the font size back. There are a few (games) I won’t be able to play in this setup, and a couple more I can play by adjusting the font size, but overall it’s definitely an improvement on the stock experience.


Adjusting the font size using an app like Font Size Setter is the easiest and quickest way of getting an overall larger font, and easy to turn off if needed. Changing the DPI can have more of an effect in some places (eg the status bar) but doesn’t work in some apps and can be a longer process to change back and forth. What works best for one person and one app, won’t necessarily work across the board so it’s a matter of trial and error to find the best setup. What setup have you found that works best for you personally? Please let me know!


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