Relationship between font size and content's perceived length

Question

My site has long form content. I need to understand if having a large font size, though it helps in readability, may lead to perception that content is longer than it is thereby making less people read it (such as people constrained for time). End of the day the end goal is to get content read.

Currently site typography and font is as below:

• Lucida Sans
• Font Size : 22 px
• Line Height : 33px
• Line Width : 55-75 characters including spaces

The above details are in sync with what I found on Smashing Magazine in terms of guidelines.

PS:I now understand setting font size in px is not appropriate after reading other threads on the forum.Hence something to fix.

Answer 1

If content is engaging, people will read it.

That should be enough. You can fine tune your content's copy as much as you want, but you'll need to communicate something, and depending on what you want to communicate, lengths of content blocks will vary.

Think about this: an e-commerce site will probably have short blocks of content, because they'll want you to focus on the CTA. On the other side, a news site could span articles through many many scrolls, even different pages

So, the first thing to know is how to deal with these content blocks, and once you define the layout and structure, think of typography.

Paul Olyslager has a very interesting article about this: The Optimal Text Layout is More Than Line Length . I'm borrowing part of his conclusions below:

The optimal text layout is difficult to define due to the relationship between its variables. For example, long line lengths are said to need more interlinear spacing to ensure that the eyes locate the next line down accurately when executing a return sweep towards the end of the line. (...)

There are, however, some guidelines to help you out:

• 12 point size font as an absolute minimum,
• don’t condense letter spacing,
• when changing line length, change the leading accordingly,
• Remember: optimal is not necessarily fastest reading line length but is the size preferred by the users,
• think about the impact on line length and leading when changing font size,
• keep the text layout clean and uncluttered and use enough white space.

Formulas everywhere

Whether you know it or not, design has countless scientific formulas, and typography is probably the aspect of design where formulas are more useful: they were needed since Guttenberg, they are needed in nowaday's most complex application. If you want to know the formulas for layouts and typography, take a read to Secret Symphony: The Ultimate Guide to Readable Web Typography, which deals with Golden Ratio concept and seamlessly apply to most designs (you can test it if in doubt).

If you're looking for research, I recommend the papers Effect of Character Spacing on Text Legibility, The Effect of Letter Spacing on Reading Speed in Central and Peripheral Vision and Eye movements, the perceptual span, and reading speed (some parts aren't specific to your issue, but useful as a whole)

In short

If you read the above cited documents and study the formulas and research on the subject, you'll quickly find different strategies to apply to your content in a consistent way. However, as in everything UX, you'll need to test and research your specific scenario

Answer 2

With this little hack to google analytics, you should be able to track scroll depth to see just how far down the page visitors were scrolling. this will help to break down the content of the page in to segments.

Also, Golden Ratio Typography Calculator will help you to get an idea about the font size to line-height ratio depending on the content width.

Answer 3

This is more a question of design and typography than UX, strictly speaking, given that UX is not really about typography. What you're talking about is readability, as opposed to legibility.

Legibility depends on how easy it is to read a block of text. Legibility is affected by serifs, open counterspaces, large x-heights, line length, type size, font weight, leading, line length, type size, font density. Readability, is how much the reader wants to read. You can improve readability by breaking the text up into smaller chunks, using drop-caps to draw the eye, using white space effectively, using a pleasing grid.

Having a larger font size will probably not trick your readers into thinking that a large block of text is smaller than it is, but it may help them want to read it more. And the font size should depend on whether or not your readers are viewing this copy on a desktop computer or a mobile device.

In this case, I would not recommend using a sans-serif font for body copy, if there are blocks of unbroken text. For that, serif fonts are far easier to read. You can use a serif or sans-serif font for the headlines.