UX Crash Course: Stupid Question 18 of 30

You may have noticed a theme in the questions so far. Everybody wants to know the one right answer instead of understanding how things work. That’s the “get rich quick” version of UX.
And today’s question is no different:

“What is the best font size?”


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Originally, this question came from a UX forum.

The designer asking the question wanted to know which size of font would be the one size to rule them all, to use now and forever, on all projects, until death do you part. 

I think the full original question was “What is the best font size on a screen?” Same same. 

Spoiler alert: the world isn’t that simple.

The other side of this question is style. Typography enthusiasts might argue that specific typefaces were designed to be shown at a certain size, and enlarging Times New Roman to 144 pt headlines will bring the wrath of God down upon you. 

Was “Thou shalt not inappropriately re-size a typeface” the 4th commandment, or the 5th? I can never remember. The one about other people’s wives always distracts me.

Anyway, even if a typeface might look like shit at huge sizes, those are not the answers you are looking for.


The stupid answer:

Web browsers set the default text size to 16 px (1 em) and smart people make browsers, so obviously that is the best font size.

(Browser designers might agree with this, but you shouldn’t.)


The real answer:

As you may have expected: there is no “best” font size. 

The best font size for any design is the one that allows the user to read the content easily. Style considerations should come after readability on your priority list.


Why this isn’t a dumb question:

There is a science to choosing font sizes.

In a nutshell, the size of your text is determined by the distance the text will be from the user’s face (normally).

If the text will be held close, like a book or a tablet, it can be smaller. If it will be held a little further, like a phone, it should be a bit bigger.

If it will be really far away, like the signs at the airport or a billboard, it should be very big.

But all of these different type sizes should aim to make text roughly the same size to the user’s eyes.

iA, the creators of the app called Writer and esteemed designers of newspapers, wrote this article on responsive typography. It includes a great diagram of a person and the size of text as it gets farther from that person.


Once you start thinking about text sizes like that, you will see all devices and screens as a spectrum. Not individual cases.

When your phone, and your tablet, and your laptop, and your huge desktop screen, and the big-screen television in the conference room are each at the normal distance from the user, the “best” font sizes should look roughly equal on all of those devices from the user’s point of view, even though the technical font sizes will all be different (16px, 24px, 72px, etc.)

Many questions in UX can be answered by looking at the world as a user rather than as a designer.


Tomorrow we will answer a stupid question as old as time itself: “Are circles better than squares?”