Core Web Vitals: LCP – What It Is and How to Improve It for SEO

In May 2020, Google announced that “core web vitals” would be part of a ranking algorithm update set to hit in 2021 called page experience.

With the page experience update now rolled out, I wanted to revisit this topic. I’ll add a few more tips we’ve learned in the intervening months by helping many websites improve their core web vitals scores. Mostly, I want you to be able to take advantage of the potential ranking benefits for your well-tuned webpages.

Core web vitals measure core elements of a webpage that enhance user experience. Google has identified three core web vitals:

• Largest Contentful Paint (LCP)
• First Input Delay (FID)
• Cumulative Layout Shift (CLS)

This article is part of our series on the Page Experience update. Here I’ll discuss LCP or largest contentful paint:

• What is LCP?
• How do I measure LCP?
• How does LCP impact SEO?
• How can I improve my LCP score?
• FAQ: How can I optimize my website’s user experience and SEO ranking using core web vitals?

What Is Largest Contentful Paint (LCP)?

LCP measures webpage load performance. More specifically, LCP measures how fast the webpage’s largest image or text block renders.

Google discusses LCP here:

Largest Contentful Paint (LCP) is an important, user-centric metric for measuring perceived load speed because it marks the point in the page load timeline when the page’s main content has likely loaded—a fast LCP helps reassure the user that the page is useful. …

How Is Largest Contentful Paint (LCP) Measured?

Google states that in order to provide a good user experience, the largest image or text block should render on the webpage within the first 2.5 seconds.

Google’s LCP score

LCP documentation specifies which types of elements are considered for LCP, and include:

• Images
• Video
• Background images loaded via CSS
• Heading tags
• Tables
• Lists
• Any other block element with text

Here’s an example of when the largest element of the page (a paragraph of text) renders before any other elements on the page:

“Largest contentful paint,” Google Developers

The goal is to hit the recommended target loading speed on most of your pages. Google says “if at least 75 percent of page views to a site meet the ‘good’ threshold, the site is classified as having ‘good’ performance for that metric.” You can learn more about how Google defines its thresholds here.

How Does Largest Contentful Paint (LCP) Impact SEO?

We know that Google values a fast site and that things like page speed are already in its ranking algorithm. LCP is another way to ensure that webpages load fast so your website visitors have a good user experience and stay on your site.

So if you already have a fast site, are you in the clear? Not exactly. According to a study by Screaming Frog, the majority are not prepared for the LCP thresholds.

Data shows that less than half of the websites studied (across 20,000 URLs) were considered good. Specifically, 43% of mobile and 44% of desktop URLs had a good LCP. The average render time was 3.13 seconds for mobile and 3.04 seconds for desktop.

In that study, the research correlated LCP and search rankings. The data is interesting, but there are too many factors to be able to say for certain how LCP influences rankings today.

“How Many Sites Pass the Core Web Vitals Assessment?,” Screamingfrog.co.uk

As an incentive for website publishers to improve their performance metrics, Google shows a “fast page” label in search results on Android that have historically met or exceeded the thresholds for core web vitals, including LCP.

Websites with this label may see an uptick in organic traffic and time on site.

How Do I Improve My Largest Contentful Paint (LCP) Score?

Google provides tools to measure LCP in a lab and in the field, including:

• Search Console (field)
• PageSpeed Insights (lab and field)
• Web Vitals Extension (lab)
• WebPageTest (lab)
• Chrome UX Report (field)
• Chrome DevTools (lab)
• Lighthouse (lab)

When it comes to lab versus field data, both can be useful. Lab is important for testing and working on improving your scores. You will get a greater variance in results, but lab data provides instant feedback.

Field data is more important when you’re trying to get the overall view of your site. The values represented will depend a lot on your users’ environments, for example, mobile versus desktop, their internet speed, their computer performance, etc. The field data is nice because it gives you an idea of how your site is performing for everyone, not just how it performs for you.

You can also measure LCP with the web-vitals JavaScript library, and you can learn more about that here. This is useful if you have your own reporting or you want to build it into other reports.

To get started, Google provides a general roadmap for how to use the tools provided to diagnose a core web vital. Out of the following list, the first three are good. I would wrap up after the third bullet by saying to publish your changes and start seeing the benefits of increased performance. The remaining bullets (4th to 6th) are “nice to haves.” The last bullet likely won’t apply to 90% of websites.

• Use Search Console’s new Core Web Vitals report to identify groups of pages that require attention (based on the field data).
• Once you’ve identified pages that need work, use PageSpeed Insights (powered by Lighthouse and Chrome UX Report) to diagnose lab and field issues on a page. PageSpeed Insights (PSI) is available via Search Console or you can enter a URL on PSI directly.
• Ready to optimize your site locally in the lab? Use Lighthouse and Chrome DevTools to measure Core Web Vitals and get actionable guidance on exactly what to fix. The Web Vitals Chrome extension can give you a real-time view of metrics on desktop.
• Need a custom dashboard of Core Web Vitals? Use the updated CrUX Dashboard or new Chrome UX Report API for field data or PageSpeed Insights API for lab data.
• Looking for guidance? web.dev/measure can measure your page and show you a prioritized set of guides and codelabs for optimization, using PSI data.
• Finally, use Lighthouse CI on pull requests to ensure there are no regressions in Core Web Vitals before you deploy a change to production.

In general, LCP is impacted by the following:

• Server and/or software response times
• Webpage resources and bandwidth
• Browser software and plugins
• Site JavaScript and CSS code

Many of the things Google suggests when it comes to optimizing LCP are things you may already be doing as part of a good SEO strategy to create a faster site.

Some tips to keep in mind as you are optimizing:

• Text will render faster in most cases than other items that need to be fetched separately (like images). So using things like heading tags as the larger elements is a good idea.
• Design changes may be needed in some cases where the largest contentful item is just too slow.
• Optimizing your JS and CSS will help load times. Be wary of including too many third-party scripts.
• The LCP is in the viewport for mobile or desktop. Things in your footer are not likely to count, so this really is focusing on the top of your page.
• You should be able to see your LCP element above the fold if you visit the page with JavaScript turned off.
• If your LCP element is an image, consider inlining it in your HTML with a data URI.

For more about this algorithm update, read the rest of our page experience series:

1. What’s the Page Experience Update?
2. How to Make a Mobile-Friendly Site
3. Intrusive Interstitials & Why They’re Bad for SEO
4. HTTPS for Users and Ranking
5. Core Web Vitals Overview
6. Core Web Vitals: LCP (Largest Contentful Paint)
7. Core Web Vitals: FID (First Input Delay)
8. Core Web Vitals: CLS (Cumulative Layout Shift)

Need to go more in-depth on this topic? I invite you to watch our on-demand webinar 3 Expert Tips to Improve Core Web Vitals. The extended Q&A at the end may just answer your toughest CWV questions!

FAQ: How can I optimize my website’s user experience and SEO ranking using core web vitals?

Optimizing your website’s user experience and SEO ranking has become paramount. Core web vitals, a set of user-centric metrics introduced by Google, play a pivotal role in achieving these goals. In this whitepaper, we’ll explore how you can leverage core web vitals to elevate both the user experience and your website’s SEO ranking, backed by expert insights and practical tips.

Understanding the Significance of Core Web Vitals

Core web vitals encompass three essential metrics: Largest Contentful Paint (LCP), First Input Delay (FID), and Cumulative Layout Shift (CLS). These metrics gauge loading speed, interactivity, and visual stability, respectively. Google emphasizes these metrics because they directly impact user engagement and satisfaction. A seamless user experience fosters longer sessions, lower bounce rates, and improved SEO rankings.

Elevating User Experience and SEO Ranking

To optimize the user experience and SEO ranking using core web vitals, consider these expert tips:

Prioritize Loading Speed (LCP): Accelerate loading times for the largest content element on your pages, such as images or text blocks. Compress images and minimize server response times to ensure quick rendering within the first 2.5 seconds.

Enhance Interactivity (FID): Reduce First Input Delay by optimizing JavaScript code and minimizing main thread tasks. This enhances page responsiveness and provides a seamless browsing experience.

Maintain Visual Stability (CLS): Avoid unexpected layout shifts by specifying image dimensions and setting a proper size attribute for multimedia content. This prevents content from shifting, providing visual consistency.

Monitor and Iterate: Regularly monitor your core web vitals using tools like Google’s PageSpeed Insights and Search Console. Iterate your optimizations based on feedback and evolving best practices.

Optimizing your website’s user experience and SEO ranking through core web vitals requires a meticulous approach. By understanding and fine-tuning LCP, FID, and CLS metrics, you can provide users with a seamless and engaging browsing experience while boosting your site’s visibility and ranking in search results. Stay informed, adapt to evolving standards, and make data-driven improvements to stay ahead in the digital landscape.

Step-by-Step Procedure: Optimizing User Experience and SEO with Core Web Vitals

1. Assess Current Performance: Use Google’s tools to measure core web vitals metrics on your website.
2. Identify LCP Elements: Determine the largest content element on each page for LCP optimization.
3. Optimize Images: Compress images without compromising quality to enhance loading speed.
4. Minimize Server Response Time: Work on server-side optimizations to reduce delays.
5. Optimize JavaScript: Minimize and defer non-essential JavaScript to improve FID.
6. Specify Image Dimensions: Set explicit image dimensions to prevent unexpected layout shifts.
7. Manage Multimedia Content: Use appropriate attributes for multimedia content to maintain visual stability.
8. Use Monitoring Tools: Regularly check core web vitals using Google’s PageSpeed Insights and Search Console.
9. Prioritize User Experience: Implement changes that improve user engagement and satisfaction.
10. Iterate and Refine: Continuously monitor metrics, gather insights, and refine your optimizations.
11. Stay Updated: Keep up with industry best practices and algorithm updates to maintain optimal performance.
12. Analyze Data: Utilize data-driven insights to make informed decisions for further improvements.
13. User-Centric Approach: Ensure that optimizations enhance user experience and engagement.
14. Test Across Devices: Evaluate your website’s performance on various devices and browsers.
15. Address Feedback: Respond to user feedback and address issues promptly.
16. Collaborate with Developers: Work with web developers to implement technical optimizations effectively.
17. Stay Consistent: Maintain a consistent monitoring, optimizing, and refining approach.
18. Adapt to Changes: Adjust strategies as core web vitals standards evolve.
19. Utilize Expert Resources: Refer to trusted sources for up-to-date information and guidance.
20. Measure Success: Track improvements in user experience metrics and SEO ranking over time.

Bruce Clay is founder and president of Bruce Clay Inc., a global digital marketing firm providing search engine optimization, pay-per-click, social media marketing, SEO-friendly web architecture, and SEO tools and education. Connect with him on LinkedIn or through the BruceClay.com website.

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