# CLS (Cumulative Layout Shift)

> Measures visual stability by tracking unexpected layout movements.

Source: https://anotherseoguru.com/en/glossary/cls

Cumulative Layout Shift (CLS) measures how much page content unexpectedly shifts during loading. High CLS frustrates users when elements move as they try to interact with the page.

## Example

Good: <0.1, Needs Improvement: 0.1-0.25, Poor: >0.25. A button that moves as an ad loads above it = high CLS.

## How to apply it

Set explicit dimensions for images/videos, reserve space for ads/embeds, avoid inserting content above existing content, use CSS transform for animations.

> **Pro tip:** Ads are often the biggest CLS culprits. Reserve exact pixel dimensions for ad containers to prevent shifts when ads load.

## Related terms

- [Page Experience](https://anotherseoguru.com/en/glossary/page-experience)