A Deep Dive into Largest Contentful Paint

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September 3, 2022


In the ever-evolving realm of web development, there are several metrics developers and tech leaders should stay tuned to for ensuring top-notch website performance. Among these, Largest Contentful Paint, or LCP, is one that holds crucial significance. As Google shifts its focus to user-centric performance metrics, understanding LCP and its role within Core Web Vitals becomes vital for developers and SEO strategists alike. But what exactly is LCP? How does it affect web performance? And more importantly, how can you optimize it? Read on as we unravel the answers to these questions and explore the intriguing concept of LCP.

What is Largest Contentful Paint (LCP)?

Largest Contentful Paint is a metric that measures the loading performance of a webpage. To be more specific, it quantifies the time taken from when the page starts loading to when the largest text block or image element is rendered within the user's viewport. In simpler terms, it tracks the point in the page load timeline when the main content is likely to have loaded.

The choice of LCP as a metric is based on a practical observation: users can't interact with a website until its largest content element, which often carries the bulk of information, is visible. The quicker this element becomes visible, the sooner the user perceives the site as loaded, which is key to a positive user experience.

But why do we focus on the 'largest' element, you might wonder? This emphasis stems from the fact that larger elements usually take longer to load and are more likely to affect the user's perception of the load speed. Hence, LCP is a potent tool to evaluate and improve a site's perceived performance.

LCP and Core Web Vitals: A Vital Connection

Core Web Vitals, introduced by Google, is a set of performance metrics aimed at measuring the user experience of a website. They comprise three crucial parameters: Largest Contentful Paint (LCP), First Input Delay (FID), and Cumulative Layout Shift (CLS). Each of these vitals assesses a distinct aspect of the user experience: loading performance (LCP), interactivity (FID), and visual stability (CLS).

LCP, being one of these three vitals, is a fundamental part of this user-centric performance model. A good LCP helps ensure that the page is useful to the user sooner, which is why Google recommends an LCP of less than 2.5 seconds for at least 75% of page loads. Pages that don't meet this standard could risk a lower ranking in Google's search results, demonstrating the SEO relevance of this performance metric.

So, not only does LCP have a direct impact on user experience, it also has indirect effects on site visibility and organic traffic, reinforcing the importance of optimizing this metric.

How LCP Affects Web Performance

To understand how LCP impacts web performance, it's important to acknowledge that the user's perception of performance is largely about speed. Users expect web pages to load fast, and even minor delays can lead to frustration,

higher bounce rates, and lost conversions. LCP, as a load time metric, is directly tied to this user perception.

Largest Contentful Paint reflects the time when the page's main content becomes visible, which, for users, often translates to when the page is 'ready' or 'loaded'. Therefore, a high LCP value could give the impression of a slow-loading page, potentially affecting the user's overall experience negatively.

Additionally, since LCP is part of Google's Core Web Vitals and therefore factored into its page experience signals, poor LCP scores can also impact a website's search ranking, diminishing its visibility and organic reach.

Calculating Largest Contentful Paint

To measure LCP, we need to identify the largest content element visible in the viewport during the page load process. This can be an image (including background images), a video's poster image, or a block-level text element. Inline SVGs and elements with CSS shapes or masks can also be considered as potential largest elements.

Once the largest element is identified, the LCP score is the time taken from when the page starts loading to when this element's render process is completed. It's crucial to note that this timing doesn't indicate when the element's loading started, but when it finished rendering on the screen.

A variety of tools can assist you in calculating and analyzing LCP, including:

  • Chrome User Experience Report (CrUX): A public dataset from real-world Chrome users that includes LCP values, among other metrics.

  • PageSpeed Insights: A Google tool that provides LCP data and performance analysis of both mobile and desktop versions of a site.

  • Chrome DevTools: Allows developers to measure LCP in the lab during the development process.

  • Search Console's Core Web Vitals report: Provides a comprehensive overview of a website’s performance, including LCP issues, on a URL-by-URL basis.

Improving LCP for Better Performance

Now that we understand what LCP is and how to calculate it, let's move onto the more actionable part: improving your LCP score. Here are some strategies:

  1. Optimize your images: Large images often contribute to a high LCP time. Optimize them by compressing without losing quality, using appropriate dimensions, and leveraging modern formats like WebP.

  2. Preload important resources: Use the 'preload' link rel attribute to load key resources as soon as possible.

  3. Remove any unnecessarily third-party scripts: These can block the main thread, delaying rendering of the largest contentful element.

  4. Upgrade your web host: A faster server response time results in quicker data delivery.

  5. Use a Content Delivery Network (CDN): CDNs deliver content from the server closest to the user, reducing network latency.

How Loado Can Help Optimize LCP

At Loado, we understand the significance of performance metrics like LCP. Our easy-to-use real-user monitoring tool helps developers, product teams, and marketers analyze and improve Core Web Vitals metrics, including LCP.

Our tool collects these metrics from users' browsers, giving you a real-world picture of your site's performance. With this data at your disposal, you can identify what's affecting your LCP time and strategize ways to improve it, optimizing your site's performance and SEO.


In the ever-evolving world of web performance, Largest Contentful Paint has emerged as a vital metric, playing a significant role in evaluating user experience and influencing SEO. By understanding what LCP is, how to measure it, and strategies to improve it, you can ensure your website delivers a superior user experience, ranks better in search results, and ultimately, drives more traffic and conversions. At Loado, we're here to help you in this journey towards better web performance.

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