---
title: "Cumulative Layout Shift"
description: "Cumulative Layout Shift (CLS) is a Core Web Vital that measures the total amount of unexpected visual movement of page content during the loading process."
category: "Technical SEO"
date: "2026-03-05"
url: "https://getbeast.io/glossary/cumulative-layout-shift/"
type: "glossary"
---

# Cumulative Layout Shift

**Category:** Technical SEO | **Updated:** 2026-03-05

Cumulative Layout Shift (CLS) is a Core Web Vital that measures the total amount of unexpected visual movement of page content during the loading process.

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## What Is CLS?
Cumulative Layout Shift (CLS) quantifies how much visible content shifts unexpectedly as a page loads. It measures the sum of all individual layout shift scores throughout the page's lifecycle. A good CLS score is under 0.1; poor is over 0.25. Layout shifts are caused by images without dimensions, dynamically injected content, web fonts, and ads loading above the fold.

## Why CLS Matters
Layout shifts frustrate users — clicking a button only to have the page jump and accidentally clicking something else is a terrible experience. CLS is a Core Web Vital and a Google ranking factor. Pages with high CLS provide poor user experiences and may rank lower.

## How to Improve CLS
Always set width and height attributes on images and videos. Reserve space for ads and dynamic content with CSS. Use `font-display: swap` for web fonts. Avoid inserting content above existing content after page load. Test with Chrome DevTools Performance panel.

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## Related Terms

- [Core Web Vitals](/glossary/core-web-vitals/)
- [Largest Contentful Paint](/glossary/largest-contentful-paint/)
- [Interaction to Next Paint](/glossary/interaction-to-next-paint/)
- [Page Speed](/glossary/page-speed/)

## Further Reading

- [Core Web Vitals Guide](/blog/core-web-vitals/)

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*Part of the [GetBeast SEO Glossary](/glossary/). Visit [GetBeast.io](https://getbeast.io) for professional SEO and log analysis tools.*