2.3.1 Three Flashes or Below Threshold (Level A) — WCAG 2.1
WCAG 2.1 Success Criterion 2.3.1 Three Flashes or Below Threshold (Level A): what it requires, a common e-commerce accessibility failure, and how to fix it.
This is educational technical reference content, not legal advice. It explains what WCAG 2.1 requires and how to meet it — not whether a specific site carries legal risk. Compliance with WCAG, the ADA, or any other accessibility law or standard is a legal determination; consult qualified counsel for legal risk assessment.
WCAG 2.1 guidelines hub → Operable → 2.3.1 Three Flashes or Below Threshold
2.3.1 Three Flashes or Below Threshold (Level A)
What it requires: Content must not flash more than three times in any one-second period, unless the flash is small enough and low-contrast enough to fall below the general flash and red flash thresholds defined in the standard. This exists to prevent triggering photosensitive seizures.
Common failure: A rapid-flashing “SALE” banner animation or a strobing background effect on a promo page exceeds the flash-rate threshold.
Fix it: Avoid rapid strobing/flashing effects entirely in marketing animations; if flashing is unavoidable for a specific effect, keep it under three flashes per second and verify against the general flash and red flash thresholds.
In 2.3 Seizures and Physical Reactions: 2.3.2 Three Flashes →
This is educational technical reference content, not legal advice. It explains what WCAG 2.1 requires and how to meet it — not whether a specific site carries legal risk. Compliance with WCAG, the ADA, or any other accessibility law or standard is a legal determination; consult qualified counsel for legal risk assessment.
This page was drafted with AI assistance and reviewed by a person for accuracy before publication.