Use of text can make or break a science picture. You can easily apply the Goldilocks Rule to text, just like you can with color: “Avoid extremes—except for a good reason!”
With text, the best way to avoid extremes is to always keep in mind that legibility matters most. Text has no purpose in a science communication if people can’t read it! If your text is extreme in some way—too small, too light, too bold—it impairs legibility. So, when making choices about your text, ask yourself, “Is it as legible as it could be?”
In this blog post, we’ll look at some features of text to see what legibility means in practical terms. We cover more aspects of text in the full SPARK course, so be sure to check it out!
Text size
The size of your text will have a big impact on legibility. Text size is measured in points and, as you can see, there are many options available:

So…what’s the best size to use? Well, this is actually a very tough question. Because the answer is: it all depends on how your audience will see your picture!
If you’re creating a picture that will be printed, you should follow the instructions provided by the publisher, if available. You can check the legibility of your text by printing your picture at the final size your audience is likely to see it.
For presentations, think big! A common mistake is to simply insert a picture that was created for publication into a slide. The text is likely to be much too small to be legible in your slide.
Your picture might end up being seen in a variety of different ways. If so, it’s best to make a different version of your picture for each different use. That way, you can choose the most legible text size for each version.

Font
Another choice you’ll need to make about your text that will affect its legibility is the font, sometimes called “typeface.” And there are many options! In fact, this is when it’s really important to remember the Goldilocks rule: avoid extremes. As with color, it’s tempting to choose something that seems exciting or creative. However, this would be a mistake. Instead, choose something that’s not extreme or distracting—choose a standard, legible font, such as Helvetica.
Helvetica is a good choice because it’s simple. It’s a style of font that’s considered to be the most legible for small amounts of text—like your labels, captions and titles. Here are several very common and legible fonts that are good choices for science pictures. Myriad Pro is the font we use throughout our SPARK online course.

Now, even within a single font such as Myriad Pro, there are still many choices: light, condensed, italic, bold, and more. Once again, avoid extremes. For most of your text, choose the standard version of your font. It’s often called “regular.”
If, in part of your picture, you have a small amount of text that you want to emphasize, simply use a bold version of the same font. In most cases, don’t use all capital letters. A bold version of your font will be easier to read than all caps.

Be concise and serve text in chunks
As you finish up your picture, it’s a good time to perform some final visual triage on your text. Are there any labels, captions, or words you can eliminate? Avoid using jargon and be concise. Less text will give you more legibility.
Being concise will also help you serve your text in bite-sized chunks. We recommend using chunks of text similar to that found in the example below. There are only about 8 words in each line and generous spacing between the lines.

Text lines that are long are difficult to read. They’re even more difficult to read when the spacing of the lines is close together. Avoid these choices (see example below).

Always keep accessibility in mind
More contrast is better for accessibility. You can check the contrast of your text using an online contrast checker. While these are primarily designed to check the contrast of website text because there are web guidelines for accessibility, they are useful tools for checking the contrast of any text.
ALL CAPS is generally discouraged unless there’s a good reason. For example, you might use all caps to emphasize a single word or two (but no more). Otherwise, all caps is an added challenge for people with visual or cognitive impairments, and it’s even hard to read for those of us without impairments. Never use all caps for blocks of text.
By following these best practices for text, you can greatly improve the legibility and effectiveness of your science pictures. For more guidelines about text, as well as other visual communication strategies, check out our SPARK online course!