August 18 2023

Lighthouse VS Core Web Vitals. What are they and what are the differences?

Understand the similarities and differences between Google Lighthouse and Google Core Web Vitals.

In the digital age, website performance is critical. Not only to provide a smooth user experience but also to make sure that the site can compete effectively in the vast online world. In this context, terms such as “Lighthouse” and “Core Web Vitals” are often used in the world of the web. However, while they are both related to web performance and are both products of Google, they are not the same thing. Very often, we tend to confuse these two terms, using one instead of the other. This post is intended to clarify what Lighthouse and are Core Web Vitals and to highlight their differences.

Google Lighthouse: A complete view of your site's performance

Lighthouse was born from a very simple but powerful idea: to provide developers with the tools they need to create high quality websites. Google has recognized the growing importance of having web pages that are not only fast, but also accessible, optimized and ready for the ever-changing needs of the modern web. Therefore, in 2016, Lighthouse made its appearance as a response to this need.

Over the years, Lighthouse has undergone multiple updates, adding new metrics and improvements, quickly becoming a de facto standard for web developers looking to optimize the performance and accessibility of their sites.

Lighthouse represents Google's ambition to create a better web for everyone by providing developers with the tools they need to make that vision happen. Through the use of this tool, Google hopes to encourage a higher standard for websites while ensuring they are ready for the future of the web.

How Lighthouse Works and its Measurement Methodology

Lighthouse works like an auditor for your website, running a series of checks to evaluate how your site performs in several categories, including performance, accessibility, best practices, SEO, and PWA. When you crawl with Lighthouse, it simulates a user visit, loading the page in a controlled environment and recording how the site behaves during this simulation.

The process begins with Lighthouse creating a new instance of the browser, making sure that the test takes place under reproducible conditions, free from outside interference. During page load, Lighthouse records various data, such as time taken to display the first useful content, time until interactivity, and many other metrics. This data is then aggregated and evaluated against a set of pre-established standards.

In addition to these basic measurements, Lighthouse also performs a number of specific audits, such as verifying accessibility practices, analyzing SEO elements and evaluating PWA features. These audits are performed through a combination of static site code analysis and real-time site execution.

Once the scan is complete, Lighthouse provides a detailed report, presenting a score for each category analyzed. These scores range from 0 to 100, with higher values ​​indicating better performance. In addition to the scores, the report also offers practical suggestions on how to improve in areas where the site may not have scored optimally. This guided approach allows developers to have a clear indication of areas for improvement and specific actions to take.


    • Page Load Time: One of the main factors influencing user experience is how fast a page loads. Lighthouse checks how long it takes for your page to fully load, allowing you to spot any obstacles slowing down the process.
    • Interactive Speed: Not only does it matter how fast a page loads, but also how quickly it becomes interactive and responds to user actions. Lighthouse measures this speed, ensuring that users don't have to wait to interact with your site.
    • Other Metrics: Lighthouse also looks at metrics like speed rating, first input delay, and resource usage efficiency.


      • Navigability: Lighthouse controls how easily users navigate your site, making sure features are intuitively placed and easy to find.
      • Compatibility for Disabled: This tool verifies that your website is also accessible for users with disabilities, by examining factors such as the presence of text alternatives for images and the correct use of labels.

Best Practices:

    • Security: Lighthouse reviews your site's security, identifying any vulnerabilities and suggesting ways to harden it against potential attacks.
    • Performance and SEO: In addition to speed, Lighthouse provides recommendations for optimizing your code, reducing resource size, and implementing caching techniques.
    • General Practices: We also provide feedback on how to improve user experience, avoid outdated content, and use modern APIs.


    • Optimization: Lighthouse analyzes your site to make sure it's structured to be easily indexed by search engines, checking things like meta tags, URL structure, and textual content.
    • Visibility: The tool also verifies that your site is visible and easily crawlable by search engine bots.

Progressive Web Apps (PWAs):

    • Compatibility: Lighthouse checks if your site can be turned into a PWA, a web version of an app that can be installed on the user's device like a traditional application.
    • User Experience: PWAs offer offline functionality, push notifications, and a native app-like user interface. Lighthouse evaluates whether your site offers these features, ensuring a smooth and native experience for users.

Core Web Vitals: The essence of web performance according to Google

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In the vast ecosystem of web tools and metrics, Google has introduced i Core Web Vitals as a response to the growing need to provide a quality user experience. But before we dive into the specific metrics, let's briefly delve into the history and evolution of this initiative.

Google has always placed the user at the center of its philosophy. With the advent of mobile and the increasing complexity of websites, the need for a smooth and responsive user experience has become ever more crucial. In 2020, Google announced i Core Web Vitals as part of their efforts to provide clear and unified metrics that reflect the most essential aspects of user experience on the web.

Unlike Lighthouse, which offers a complete and multifunctional panorama of the quality of a website, i Core Web Vitals boil down to three key metrics, each of which focuses on a core aspect of user experience:

  1. Largest Contentful Paint (LCP): This metric measures loading performance and refers to the time it takes for the page to display the main visual content. In essence, it indicates how long it takes for the user to see the main content of the page. A good LCP assures the user that the page is useful.
  2. First Input Delay (FID): FID measures responsiveness by measuring the time between when a user first interacts with a page (for example, when they click a link or button) and when the browser is actually able to respond to that interaction. An optimal FID ensures that the page is responsive to initial user actions.
  3. Cumulative Layout Shift (CLS): This metric is about visual stability. Evaluate how often users experience unexpected changes in the layout of a page, without them being caused by direct interaction. A low CLS ensures that the page does not experience unexpected visual changes.

The presentation of Core Web Vitals by Google it was not just a technical announcement. It sent a clear message to the world of web development: user experience is key. While specific metrics may evolve over time, Google's goal with i Core Web Vitals is to establish a set of standards that can guide developers towards creating high quality web experiences. And, given Google's dominant role as a search engine, these metrics have quickly become crucial to not only providing a great user experience, but also visibility in search results.

Similarities between Lighthouse and Core Web Vitals

Lighthouse and Core Web VitalsWhile they are distinct tools with specific goals and capabilities, they have several similarities, stemming primarily from their common origin and shared mission to elevate the quality of the web experience. Let's dive into the similarities between these two powerful tools:

  1. An Unrelenting Commitment to Web Performance: Performance is the key to a quality user experience. Indeed, both tools place a strong emphasis on it. While Lighthouse takes a holistic approach, providing in-depth analysis covering a wide range of metrics related to performance, accessibility, best practices and more, the Core Web VitalsInstead, they focus solely on three core metrics that directly impact user experience. This divergence of approaches reflects the versatility of the two tools: one for global analysis, the other for targeted measurement.
  2. Origins and Standardization by Google: Being both products of Google, Lighthouse and Core Web Vitals strictly follow the guidelines, standards and recommendations set by the research giant. This common provenance ensures that developers using these tools are always attuned to what Google considers best practices in the web world. And given Google's dominant role in the online search ecosystem, complying with these standards is not only a matter of quality, but can also have a direct impact on a site's visibility in search results.
  3. A User Oriented Vision: Both tools were created with one main goal: to ensure a great user experience. Whether it's smooth navigation, fast loading times, responsiveness or visual stability, the mission of Lighthouse e Core Web Vitals is to provide developers with clear metrics and actionable feedback. These tips, tricks and ratings are meant to guide developers towards optimizing their websites, ensuring that every visitor has a smooth and satisfying user experience.

Key differences between Lighthouse and Core Web Vitals

Google, the undisputed leader in this field, has developed two main tools, Lighthouse and Core Web Vitals, to assist in this mission. Both aim to ensure an optimal online experience for users, but how exactly do they differ? Here is an in-depth look at their distinguishing features.

  1. Breadth of Analysis: One of the most tangible differences between Lighthouse and Core Web Vitals it concerns the scope of their analyses. Lighthouse offers a holistic and detailed view of the website, covering a multitude of metrics that go far beyond simple performance. This includes loading times, accessibility, best practices, SEO, and even a site's readiness to become a Progressive Web App. Core Web Vitals take a more focused approach, focusing their attention on three essential metrics that are core pillars of user experience: loading, interactivity, and visual stability.
  2. Instrument Mode: Also in terms of how they are used, Lighthouse and Core Web Vitals have significant differences. Lighthouse offers flexibility: it can be easily integrated into the developer workflow as a Chrome browser extension or as a command-line tool, providing detailed reports and out-of-the-box recommendations. THE Core Web VitalsHowever, they don't have a similar dedicated interface, but their metrics are often collected and displayed through tools like Google Search Console, which provides developers and site owners with a snapshot of their site's overall user experience.
  3. Objectives and Approach: While both are focused on improving web performance, their perspective and how they present results vary. Lighthouse presents itself as a virtual consultant: it analyzes every corner of your site and offers detailed and personalized suggestions on how to optimize it in various aspects. His approach is that of an in-depth analysis, followed by targeted advice. Conversely, i Core Web Vitals they act as a barometer, giving developers a high-flying view of key areas of user experience. Instead of flooding you with details, they provide a clear view of where your site ranks against the essential standards set by Google for a quality user experience.

In summary, while both tools derive from the same philosophy of providing a better, more user-friendly web, they differ markedly in how they approach this mission, the metrics they use, and the feedback they provide to developers.


In the dynamic and ever-changing world of the web, the need for effective tools that ensure optimal website performance is more pressing than ever. At the heart of this revolution, we find Lighthouse e Core Web Vitals, both developed by Google, are invaluable resources for website developers and owners.

While both are born out of a desire to elevate the quality of online experiences, their nature and approach differ significantly. Lighthouse acts like a virtual consultant, examining every corner of the website, providing a detailed assessment ranging from loading times to SEO, and making targeted suggestions for any area that needs improvement. On the other hand, Core Web Vitals serves as a thermometer, offering a concise but essential view of user experience performance, focusing on three key metrics.

The key to success, therefore, does not lie in choosing one tool over another, but in understanding the peculiarities of each and knowing how to use them in combination. Used together, Lighthouse and Core Web Vitals they offer a complete overview, enabling developers to address both technical details and user experience challenges. Ultimately, a thorough understanding of these tools and the ability to use them synergistically will be key to ensuring your website not only meets but exceeds user expectations in the modern digital ecosystem.

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