# WCAG 2.2 – 2.3.1 Three Flashes or Below Threshold

- Level: A
- Principle: 2 Operable
- Guideline: 2.3 Seizures and Physical Reactions
- Introduced in: WCAG 2.0

## What the rule requires

Nothing flashes more than three times per second – or the flashing is small and dim enough to stay below the thresholds. Strong flashing can trigger epileptic seizures – this can be life-threatening.

## How to get it right

Avoid flash and strobe effects. Check videos with an analysis tool such as PEAT.

## Who benefits

- People with epilepsy

## Sources

- [This rule on wcag.dehl.net](https://wcag.dehl.net/en/wcag/2-3-1/)
- [Official W3C explanation](https://www.w3.org/WAI/WCAG22/Understanding/three-flashes-or-below-threshold)
- [Techniques (WCAG Quick Reference)](https://www.w3.org/WAI/WCAG22/quickref/#three-flashes-or-below-threshold)

_Plain-language explanation. Only the original W3C text is normative._