--- title: "Cracking the Code: Understanding Cumulative Layout Shift and How to Fix It" description: "Learn Cracking the Code: Understanding Cumulative Layout Shift and How to Fix It in this blog" author: "HARIDHA P" published: 2023-11-30 updated: 2023-12-01 canonical: https://www.mindstick.com/blog/303470/cracking-the-code-understanding-cumulative-layout-shift-and-how-to-fix-it category: "coding standard" tags: ["coding"] reading_time: 3 minutes --- # Cracking the Code: Understanding Cumulative Layout Shift and How to Fix It **Understanding [Cumulative Layout](https://yourviews.mindstick.com/view/86009/how-to-fix-cumulative-layout-shift-cls-issues) Shift (CLS):** ## Definition: Cumulative Layout Shift quantifies how much a webpage's elements shift unexpectedly during its lifecycle, from initial rendering to full interaction. ## Calculation: CLS is calculated by multiplying the impact fraction (the fraction of the viewport affected) by the distance fraction (how far the element moves). ## Significance: Visual stability is vital for a positive [user experience](https://www.mindstick.com/articles/12731/the-importance-of-feedback-to-the-user-experience). A high CLS score indicates a less predictable layout, leading to potential frustration for users. ## Why CLS Matters: ## User Frustration: Unexpected layout shifts can cause users to interact with unintended elements, leading to frustration and a poor overall experience. ## Impact on Conversions: CLS can negatively impact user trust and engagement, potentially affecting [conversion rates](https://www.mindstick.com/blog/12083/how-to-drive-conversion-rates) for e-commerce and other interactive websites. ## SEO Impact: [Google](https://yourviews.mindstick.com/view/86499/google-strict-microtargeting-for-financial-ads-to-protect-user-privacy) considers user experience metrics, including CLS, in its search ranking algorithms. A poor CLS score can affect a website's visibility in search results. ## Common Causes of Cumulative Layout Shift: **[Images and Videos](https://www.mindstick.com/forum/158315/how-do-you-create-responsive-images-and-videos-using-bootstrap-classes) Without Dimensions:** When images or videos load without predefined dimensions, they can cause layout shifts as the browser reserves space for them. ## Ads and Embeds: Ads and embedded content, especially if they load asynchronously, can contribute to unexpected shifts as they appear on the page. ## Web Fonts Loading: Web fonts loading asynchronously or with variable rendering times can cause text elements to shift when the font is applied. ## Strategies to Fix and Prevent CLS: ## Always Include Dimensions for Media Elements: Include [width and height](https://www.mindstick.com/forum/158680/what-css-property-is-used-to-set-the-width-and-height-of-an-element) attributes for images and video elements to reserve space, preventing layout shifts upon loading. ## Utilize the Aspect Ratio Attribute: For images and video elements, use the aspect ratio attribute to maintain space even before the content fully loads. ## Preload Key Resources: Preload important resources, such as fonts or critical CSS, to ensure they load promptly and minimize layout shifts. ## Minimize Asynchronous Loading: If possible, load critical scripts synchronously to control their impact on the layout. Asynchronous loading can lead to unpredictable shifts. ## Implement a Loading Screen: Use a loading screen or skeleton UI to indicate that content is still loading. This provides a visual cue and reduces the perception of layout instability. ## Prioritize Above-the-Fold Content: Load essential content above the fold first to give users immediate access to crucial information while the rest of the page loads. ## Monitor CLS Metrics: Regularly monitor CLS metrics using tools like Google [PageSpeed Insights](https://www.mindstick.com/forum/161450/how-does-pagespeed-insights-help-with-core-web-vitals) or Lighthouse to identify problematic elements and areas for improvement. ## Test Across Devices and Networks: Test your website across various devices, browsers, and network conditions to ensure a consistent and stable layout for all users. **[Challenges and Considerations](https://www.mindstick.com/forum/158646/what-are-the-main-challenges-and-considerations-in-testing-microservices):** ## Dynamic Content: Websites with dynamic content, such as user-generated posts or real-time updates, may face challenges in completely eliminating layout shifts. ## Third-Party Scripts: Third-party scripts, like those for ads or analytics, can contribute to CLS. Opt for asynchronous loading and consider their impact on visual stability. ## Continuous Optimization: CLS optimization is an ongoing process. Regularly assess and refine strategies as your website evolves. ## Conclusion: Cumulative Layout Shift is more than just a metric; it's a reflection of your commitment to providing a seamless and enjoyable user experience. By understanding the causes and implementing proactive strategies, [web developers](https://www.mindstick.com/articles/326944/top-5-essential-skills-every-web-developer-should-know) can significantly reduce the impact of unexpected layout shifts. As user expectations for a smooth and visually stable browsing experience continue to rise, addressing and optimizing Cumulative Layout Shift becomes not just a best practice but a necessity for [web development](https://www.mindstick.com/services/web-development) success. --- Original Source: https://www.mindstick.com/blog/303470/cracking-the-code-understanding-cumulative-layout-shift-and-how-to-fix-it Copyright © MindStick Software Pvt. Ltd. This Markdown version is provided for developers, AI systems, and offline reading.