Goal
Eliminate flashing content entirely (highest safety bar).
Success Criterion · WCAG 2.3.2
Three Flashes
Web pages do not contain anything that flashes more than three times in any one second period.
Level AAAWCAG 2.0Operable2.3 · Seizures and Physical Reactions
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What to do
Ensure nothing flashes more than 3 times per second (no threshold exceptions).
Why it matters
This AAA criterion removes threshold allowances to reduce seizure risk even further.
Success criterion
What WCAG 2.3.2 requires
Summarized directly from the official Understanding document so teams can quote the requirement accurately.
Web pages do not contain anything that flashes more than three times in any one second period.
Intent
Why WCAG created this requirement
- AAA aims to minimize seizure risk as much as possible.
- Even “below-threshold” flashes are avoided at this level.
- Applies to all flashing in animations, media, and interactive effects.
Benefits
Who gains when you pass
- Provides maximum protection for people with photosensitive epilepsy.
- Reduces discomfort from flashing for a wider set of users.
Why it matters
User impact when this criterion fails
Summaries drawn from the Understanding document help you socialize impact statements with product stakeholders.
If rapid flashing exists, users may be exposed to severe risk.
Users may avoid content they cannot trust to be safe.
Overview
This AAA criterion is stricter than 2.3.1: it disallows anything flashing more than three times in any one-second period, without relying on threshold exceptions.
- Prefer motion that uses smooth transitions and does not blink rapidly.
- Avoid CSS blinking, flashing alerts, and strobe-like video edits.
- Treat third-party embeds as in-scope and choose safe providers.
Reference: All summaries and highlights originate from Understanding WCAG 2.3.2 and the W3C quick reference.
Fast facts
- Conformance level
- Level AAA
- WCAG version introduced
- WCAG 2.0
- Principle
- Operable
- Guideline
- 2.3 · Seizures and Physical Reactions
Examples
Make success tangible for teams
Share pass/fail snapshots to coach designers, engineers, QA, and content authors.
Alert highlight
Pass
Alert uses a steady border and subtle pulse slower than 3 flashes/sec.
Fail
Alert rapidly flashes background color multiple times per second.
Loading indicator
Pass
Spinner rotates smoothly.
Fail
Indicator blinks on/off rapidly to show loading.
Evidence to keep
Document conformance decisions
Capture artifacts for VPATs, procurement reviews, and regression testing.
- Add a “no rapid flashing” requirement to motion design standards.
- Record a list of safe animation patterns approved for use.
Official resources
Deep dives and supporting material
Keep these links handy when writing acceptance criteria or responding to audits.
Implementation checklist
Capture progress and blockers
- Remove or redesign any rapid flashing effects.
- Set animation guidelines to ban rapid flashing patterns.
- Audit third-party content sources for flashing behavior.
- Replace legacy GIFs/animations that blink rapidly.
Testing ideas
Prove conformance with evidence
- Scan all pages for flashing content and verify no element flashes >3 times per second.
- Review media playback for strobe effects and replace/remove.
- Re-test after design updates that add motion or highlight effects.
Related success criteria