Legibility vs. Readability

Getting this next distinction right could save you hours of redesign on your next project.

“I don’t think the text in this design is legible.”

“No, it’s legible. It’s just not readable.”

“What?”

Like all the terms for levels of accessibility, “legibility” and “readability” aren’t interchangeable.

Legibility is about recognizing letters, not reading paragraphs. Legibility is influenced by factors such as viewing distance, typeface design, and the difference between the thinnest and thickest lines in a letter. Can you clearly tell the difference between a capital “I”, a lowercase “l”, and the number “1”? If so, it’s legible. Wayfinding (for example, an EXIT sign) is all about legibility.

Readability is about sustained reading comfort. Readability is influenced by legibility, how many words there are in a line of text (line length), and the spacing between lines (leading). For example, reading a book comfortably over time is all about readability.

Exhibitions can involve some of both. Titles and digital interactive texts might be more about legibility. Long intro panels might be more about readability. Object labels might be a little of each.

Here’s the thing:

Legibility is about whether you can recognize letters at all. Readability is about comfort reading whole paragraphs. Exhibitions always require legibility. They sometimes involve readability.

Warmly,
Jonathan

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MtM Word of the Day:
Line length. The number of words or characters in a line of text, usually in a paragraph (versus a title). Very long or very short lines of text aren't easy to read in a sustained way. 50-65 characters per line is a common sweet spot.