Operable · Level A · Introduced in WCAG 2.0
WCAG 2.3.1: Three Flashes or Below Threshold
Published by whatisADA / Grow Wild Agency · Updated
What this criterion means
Avoid content that flashes more than three times in a one-second period unless it is below the defined general-flash and red-flash thresholds. Evaluate video, animation and other rendered effects across the page.
A practical example
A promotional animation rapidly alternates red frames. Replace the effect with a stable transition or have the actual asset assessed with an appropriate flash-analysis method before publication.
How to check it
- Inventory videos, GIFs, animations and interactive effects that may flash.
- Use appropriate analysis of the actual rendered content rather than asking a photosensitive person to inspect it.
- Remove unsafe effects or document the measured frequency and threshold assessment for any retained material.
What can be missed
Small-looking content and a pause button do not automatically make flashing safe. The threshold analysis includes more than frequency, and this criterion is part of WCAG's non-interference requirements.
Record your test
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These are your observations, not automated results or a conformance certificate. A complete evaluation needs appropriate scope, supported technologies, all applicable criteria and relevant page states.
Primary sources and scope
This is independent implementation guidance with original examples. The linked standard contains the full definitions, exceptions and conformance requirements. A criterion or checklist alone does not establish legal applicability or whole-site conformance.