What WCAG 2.3.1 Requires
Content must not flash more than three times in any one-second period, unless the flashing is small enough or low-contrast enough to fall under the general flash and red flash thresholds, since rapid flashing can trigger seizures.
Can AccessBell Test This Automatically?
Not fully. Like most WCAG criteria that depend on meaning or context, this one needs a person to judge. AccessBell's report lists it for manual review rather than marking it pass or fail automatically, so it never gets missed.
How to Test It by Hand
Review any animation, video or ad for rapid flashing; when in doubt, use a photosensitive epilepsy analysis tool on the content.
Common Failures
- An animated ad banner flashes rapidly to grab attention.
- A loading animation flashes at a rate that exceeds the safe threshold.
Related Criteria in Seizures and Physical Reactions
WCAG 2.3.1 Questions
What does WCAG 2.3.1 require?
Content must not flash more than three times in any one-second period, unless the flashing is small enough or low-contrast enough to fall under the general flash and red flash thresholds, since rapid flashing can trigger seizures.
Can AccessBell test WCAG 2.3.1 automatically?
Not fully. This criterion needs a person to judge, so AccessBell's report lists it for manual review rather than marking it pass or fail on its own.
What level is WCAG 2.3.1?
Level A, added in WCAG 2.0.
Sources
- W3C: Understanding 2.3.1 Three Flashes or Below Threshold (opens in a new tab)
- W3C: Web Content Accessibility Guidelines (WCAG) 2.2 (opens in a new tab)
This page explains a technical standard and is not legal advice. See our disclaimer.