Smaller font sizes on smaller screen devices

Question

I'm an iOS developer and I recently had a discussion with a designer in my team about the font size of a label in an iOS app that we are producing. It is a small label that is used to present the user with their account balance. One issue is that this label was designed with a width in mind that it couldn't fit big amounts of money. The idea of making the font scalable depending on the text size is OK and easy to apply, but we reached another problem:

When using the same app on a smaller device (like an iPhone SE), the text doesn't fit the label even for considerably small amounts of money, so the solution proposed by this designer was to make the initial font size smaller on small devices so it can scale down from there when needed.

But my question is: Presenting smaller fonts to people with smaller devices wouldn't affect readability since the screen itself is already small? My idea was for him to rethink and redesign that area of the app taking into consideration different sizes of screen but he refuses to do so, insisting on the smaller font size to fix it. Are there any articles or "Good Practices" kind of documents that can support either one of these sides?

Answer 1

Changing font sizes based on the screensize of the device is something that has been discussed for quite a while. Things like Responsive Typography is one solution, where the sizing is done dynamically depending on device.

More dramatic options have also been experimented with, for instance dynamically changing the text size depending on how far your eyes are from the device

The basic premise is pretty sound though - a fontsize appears larger the closer you hold it to your face. Therefore, if the device is closer to your eyes then you can have the font smaller. After all, if you're 3' away from some text at 50pt that text is going to take up much more of your visual space when you move to 1' closer, so it makes sense to decrease the fontsize.

It is relatively well established that you should sit about 16-30" from your laptop screen, which is basically arms-length. But people don't hold a phone at arms-length. It's often about half that (Apple recommend you hold the iPhone about 10-20" from your eyes in order for FaceID to work - and that's the 'recommended' distance, not necessarily what people actually go with for regular use), so you should be able to determine a suitable formula for the ideal size for phones. There are also font size calculators out there to assist.

Answer 2

Often iOS designs aim for achieving a 1-to-1 in terms of the (shallow/naive) full screen design, even on screen dimensions that weren't considered - something must give, and if your designer won't budge then it is usability that will be sacrificed. That is poor or lackluster design. Making everything smaller isn't a great solution, expecting Users to hold the device closer to their face isn't a great solution (you want to avoid being a "needy app" in that regard).

Had the designer accounted for iOS' Accessibility feature 'Larger Dynamic Type'? There is a good chance the app won't render well even on the device(s) originally targeted in the design.

I would firstly consider removing unnecessary design requirements (i.e. ones that are problematic when it comes to a smaller screen, e.g. large margins and amounts of white space, stylistic visuals, side-by-side ordering of widgets, etc.) from the screen then look at how to compact the information - the screen is trying to capture input (for financial transactions it seems), so look-and-feel should take a back seat while productivity gains highest priority.

If the screen won't scroll or hasn't been designed to scroll yet there is enough content on it to necessitate scrolling, then that needs to be addressed (either break up the content into smaller pieces or simply allow scrolling).

If the label is positioned horizontally next to the input field, causing the input field to have to fit in a portion of the screen width: move labels vertically above the fields so the fields can enjoy full screen width.

Demographics of your user-base and those typically using older devices should be an important consideration, especially if it shows an abundance of the elderly, vision-impaired, and non-technical users.