Success Criterion 2.3.1
Conformance level A

2.3.1 · Three Flashes or Below Threshold

Lesson overview · Three Flashes or Below Threshold

In plain language

Nothing may flash more than 3 times per second (seizure risk).

Who it affects

People with photosensitive epilepsy and others sensitive to rapid flashing.

How to check

Review videos, GIFs and effects for rapid flashing; use the PEAT tool for anything borderline.

Common misconception

Marketing teams sometimes assume flashing is only a concern for full-screen strobe effects. Even a smaller flashing region can trigger seizures if it covers enough of the visual field and flashes fast enough.

Learn more

Understanding Understanding this success criterion (opens in a new tab)

Scenarios in this lesson

Content Flashing Faster Than 3 Times per Second
Strobe Intro or Glitch Effect Above the Flash Threshold
Unedited Video With Strobe or Lightning Effects
Rapid Full-Screen Color Flash on Load or Error
Ad or User-Generated Content Never Screened for Flashing
Rapid Hover Effect That Flashes When a Key Autorepeats
Loading Spinner Built as a Rapid Full-Screen Flicker
Game With Strobe Effects and No Photosensitivity Mode