Solid Vs. Outline Icons: Which Are Faster to Recognize?

UX Movement
6 min readFeb 20, 2019

When building a mobile app, there comes a time when you have to decide whether to use solid or outline icons. Which style is better for user experience?

Some think the difference between them is just a matter of preference, but research shows there’s more to it than that–one style has a faster recognition rate than the other.

Knowing when to use solid or outline icons will make it easy for your users to navigate your mobile app. They’ll be able to recognize your icons faster and select the right options.

A research study, “Filled-in vs. Outline Icons: The Impact of Icon Style on Usability,” discovered that icon style affects task performance. Task performance was measured by the speed and accuracy of recognizing and selecting icons.

Solid icons were generally faster to recognize than outline icons, but with a few exceptions. And some icons showed no difference in task time. This has to do with characteristic cues.

Characteristic Cues

Characteristic cues are what users use to identify icons. If characteristic cues are absent or hard to notice, the icon becomes unidentifiable.

For example, the tail of a comment bubble icon is its characteristic cue. Without it, it’s simply a circle. The…



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