Ensure content remains readable and legible when resized to 200%
Make sure reading remains efficient when content is set to 200% of its initial size
While web accessibility guidelines do not determine a minimum font size to be set on content, authors are encouraged to settle for a size that will make reading comfortable for most users. As a general rule, setting the font size to 100% of its default value using a relative unit measure is a safe assumption for accessibility. However, the default font size will still often proves insufficient to a lot of users who happen to have low vision. Consequently, such users will tend to rely on the browser’s built in features to increase the size of the text up to a level that allows for more efficient reading. To meet these users’ needs, authors should build pages that allow for legible and functional reading, even when the text is resized up to 200% of its original size.
To do so, simply make sure that resizing the text of the page does not cause content to be clipped, truncated, overlapped or otherwise obscured, so that it is no longer available to users. While resizing the text in this way will not guarantee that the content will remain functional for reading for everyone, it will at least ensure that up to 200%, regardless of the impact on the page layout itself, that the content will remain legible and readable. Users who require a low level of text magnification will benefit from the flexibility offered, while users who require a stronger level of magnification support will most likely rely on other assistive tools, such as specialized screen magnifying software.
User Story
As a user who has low vision, I want to be able to resize the text to at least 200% of its original size without any loss of legibility, so that I can more comfortably read the content on the page.
Simple Code Example
Not Applicable
Testing Methodology
Using the NoSquint extension for Firefox, set the primary zoom method to "text only" and increase the "Default text-only zoom level" to 200% and validate that that all text remains legible and readable (no text is clipped, truncated, overlapped or obscured).
Specification Details
WCAG 2.0: Level AA
Principle: Perceivable
Guideline: 1.4 Distinguishable
Success Criterion: 1.4.4 Resize Text
Related Technique: F69
Category: Failure