What is readability in UX design?
Readability refers to how easily users can read and comprehend text within an interface. It is determined by two interacting factors: the visual presentation of the text, including typography, spacing, contrast, and layout, and the linguistic complexity of the content itself. High readability means users can process text quickly, with low effort, and high comprehension. Poor readability forces users to slow down, reread, or give up on understanding content that may be important for completing their task.
What affects readability in interface design?
Typography significantly affects readability. Body text should be at minimum 16px on mobile and 14px on desktop. Line height of 1.4 to 1.6 for body text gives lines sufficient breathing room. Line length between 45 and 75 characters per line keeps the reading experience comfortable. Font weight should be sufficient but not so heavy that letterforms lose definition at small sizes. Color contrast must meet WCAG minimums of 4.5:1 for normal text and 3:1 for large text. See the text line length and height guide for detailed recommendations.
How does language complexity affect readability?
The linguistic complexity of content is as important as its typographic presentation. Long sentences, passive voice, jargon, and abstract language all increase the cognitive effort required to understand content. The Flesch-Kincaid readability score and similar measures estimate reading level based on sentence length and word complexity. Most interface copy should target a reading level accessible to a broad audience, typically equivalent to a 6th to 8th grade reading level. Plain language principles address the linguistic dimension of readability while typographic guidelines address the visual dimension.