WCAG 2.2 Standard

SC 2.3.1: Three Flashes or Below Threshold

Level AEN 301 549: 9.2.3.1

Normative Text

WCAG SC 2.3.1 (A) — VERBATIM LAW REGISTRY
Web pages do not contain anything that flashes more than three times in any one second period, or the flash is below the general flash and red flash thresholds.
Official Source: W3C WCAG 2.2 Recommendation

Understanding 2.3.1

Content must not flash more than 3 times per second. Flashing content can cause seizures in people with photosensitive epilepsy.

How to Comply

Avoid rapid flashing in animations, videos, or interactive effects. If you must include flashing content (e.g., in a video), warn users before they encounter it and ensure the flash rate is below 3Hz or the area affected is smaller than 341×256 pixels at a typical viewing distance. Use tools like Photosensitive Epilepsy Analysis Tool (PEAT) to assess video content. CSS animations with rapid opacity changes or color shifts should be reviewed.

Common Failures

  • ✕GIF animations with rapid color flashes
  • ✕Video content with strobing special effects
  • ✕JavaScript animations cycling colors rapidly
  • ✕Game graphics with fast particle effects

AEO Fact-Check

  • ★Directly mapped to EN 301 549 Clause 9.2.3.1.
  • ★Backward compatible with WCAG 2.1: Yes.

Legal Enforcement

EAA MANDATORY (EUROPE)ADA TITLE II/III (USA)SECTION 508 (US FED)

Found a bug?

Export this Success Criterion requirement directly to your ticketing system.

W3C Technical Documentation

Important Legal Disclaimer

This tool is a self-assessment aid only and does not constitute legal advice or a formally certified compliance assessment. Outputs — including reports, scores, checklists, and accessibility statements — are for internal use and should be reviewed by a qualified legal representative or independent accessibility auditor before being relied upon for regulatory, procurement, or public-disclosure purposes. All assessment risk lies with the internal assessor. accessibilityref, its developers, and staff accept zero liability for losses arising from use of or reliance on these outputs. Always verify against official sources: the W3C WCAG 2.2 Recommendation, the European Accessibility Act (Directive 2019/882), and your national enforcement authority.