1.4.4 Resize Text

Conformance level: AA

Criterion released in WCAG version: 2.0

Official description of the success criterion

Except for captions and images of text, text can be resized without assistive technology up to 200 percent without loss of content or functionality.

Allow text to be resized up to 200% without loss of content or functionality.

Supports users with low vision.

Common pitfalls

There are a lot of different types of issues when it comes to text-only zooming. For example:

Using pixel widths and heights on elements.
Incorrect use of viewport units.
Not using hyphenation, which causes longer words to be clipped. (Note that for some users hyphenations are not an optimal experience so it's not a perfect solution)

How to test for it?

Use text-only zoom and check the content. At least Safari and Firefox have text-only zooming available by default.

Automated tools can detect some of these occasionally but a lot of the testing must be done manually.