Don’t use large flashing images Accessibility Checkpoint

Description

Web pages must not contain large images that flash more than three times in any one second period.

Help

Flashing areas larger than 21,824 square pixels can trigger seizures in people with photosensitive seizure disorders like photosensitive epilepsy.

Applicable standards

• WCAG 2.0 (Success Criteria: 2.3.1 level A)
• WCAG 2.1 (Success Criteria: 2.3.1 level A)
• WCAG 2.2 (Success Criteria: 2.3.1 level A)
• Section 508 (2017) (Success Criteria: 2.3.1 level A)

Note: Section 508 Refresh (2017) checkpoints are equivalent to WCAG 2.0 level A and level AA checkpoints.

Change history

• 6.56 Mar 2025 Improved detection.
• 5.9 Jun 2015 Handle non-standard image tag.
• 5.6 Sep 2014 Now triggers WCAG 1 and Section 508 issue as well as WCAG 2.
• 5.5 May 2014 Fixed false positive on non-looping animated GIFs.
• 5.4 Feb 2014 Added.

This page describes a web site issue detected in HTML documents by SortSite Desktop and OnDemand Suite.

Rule ID: AccWcag2-2.3.1-1