Quick Guide To Google Lighthouse Tools [2025 Update]

Google Lighthouse’s compact and powerful auditing tool is an essential aid that every website owner or manager should know how to use. After all, how can you fix your website’s performance or SEO efficiently if you don’t have some insight into what’s going wrong?

While Google’s website management tools have certainly improved over the years, there’s no denying that a Lighthouse audit page looks intimidating. As with anything to do with websites, it’s filled with technical jargon you may not have come across before, and it’s not always easy to figure out what you need to fix.

That’s where I come in. I’ve been using Lighthouse for years to fix my websites, so I’ve written this comprehensive guide to help you learn how to run an audit, read the results, and fix any issues it might have highlighted. Let’s get started!

What Is Google Lighthouse?

Google Lighthouse is a free, open-source tool that automatically analyzes your website’s performance and quality. It measures your site’s speed and other key metrics to show whether issues are caused by your code, configuration, or page structure.

Think of it as a report card for your website, without all the fluff about being “ a pleasure to have in class” or “easily distracted by others”.

Like many of Google’s tools, Lighthouse is designed to steer websites toward meeting Google’s standards. That might sound a little self-serving, but the truth is that those standards closely align with web design best practices.

So yes, your audit results are filtered through Google-tinted glasses, but they still offer practical advice for improving user experience.

Plus, by making your website more compliant with Google’s standards, you’ll improve your website’s SEO and rankings, helping more people find you online. So, it’s really a win-win situation.

What Does Google Lighthouse Assess?

Generally, Lighthouse’s audits are broken down into four core categories: Performance, Accessibility, Best Practices, and SEO. Depending on how you run your audit, you can choose to focus on only a few of these areas.

Each section will be given an overall score from 0 to 100. You can click on a score to jump right to the relevant section and find out what areas need improvement. It’s also possible to see which audits passed, so you can note what’s working and keep it up in future updates.

You can rerun the audits whenever you like, and it’s a good way to keep track of your progress. The more problems you fix, the higher your scores will rise.

Performance

The Performance category is concerned with how quickly your website and its content load. Unlike other categories, this score is based on measurable load-time metrics. Among other things, Google assesses your performance against its Core Web Vitals metrics:

• First Contentful Paint (FCP): Time it takes for the first content to be visible to users
• Largest Contentful Paint (LCP): Time it takes for the largest element to load
• Total Blocking Time (TBT): Time before the page becomes responsive to user input
• Cumulative Layout Shift (CLS): Degree of layout movement while the page loads
• Speed Index (SI): Time it takes for the page to finish loading

Accessibility

Accessibility measures whether your website is usable with assistive technology, like screen readers. It automatically searches for common accessibility issues, like:

• Poor colour contrast
• No alt text on images
• ARIA attributes that don’t match their intended roles
• Links not having clear names
• HTML defining the language screen readers should use

This section will also prompt you to perform manual tests to find accessibility issues that are outside the scope of the tool. For example, you may need to test whether interactive elements are accessible via keyboard navigation.

Best Practices

Best Practices covers whether your website adheres to modern guidelines for user-friendliness and security, which include:

• Using HTTPS
• Avoiding third-party cookies
• Having no issues flagged in Chrome DevTools
• Protecting against attacks like clickjacking and cross-site scripting
• Loading images at appropriate resolutions

SEO

Finally, the SEO category indicates if your website is set up to appear in Google search results. Lighthouse checks to see if your website:

• Is blocked from indexing
• Has an appropriate title and meta description
• Uses links with descriptive text
• Uses crawlable links
• Has a valid robots.txt file

How To Run a Google Lighthouse Audit: 4 Ways

Lighthouse audit reports are largely the same regardless of how you run them. So, the method you choose will depend on the tools you’re comfortable with and what best fits your workflow.

1. Use the Lighthouse Chrome Extension

1. Install the Chrome browser. Because Lighthouse is a Google tool, it’s only available through the Chrome ecosystem.
2. Download the Lighthouse extension. Go to the Chrome Web Store, type “Lighthouse” in the search bar, and click the first result. Double-check that the creator is listed as “developers.google.com/web/”, as there are several unofficial extensions.
3. Go to your website. Once you’re there, click the puzzle piece icon in your toolbar to open the Extensions menu, then click Lighthouse.

4. Run a Lighthouse audit. Choose where you want to see the results, which categories you want to analyze, and whether you want the audit to cover the desktop or mobile version of your site. Then, click Generate report.
5. You’re done! Your audit report will load in a new tab regardless of the output option you choose.

2. Use Lighthouse With Chrome DevTools

1. Install Chrome. Because it’s a Google product, it comes with Lighthouse tools pre-installed.
2. Go to your website. Then, open Chrome DevTools by right-clicking anywhere on your website and selecting Inspect, or by pressing Ctrl + Shift + C.
3. Find the Lighthouse tab. Click the “>>” icon, then Lighthouse.

4. Start your audit. Ensure you have Navigation selected as the mode. Like with the Chrome extension, you can choose whether to analyze the mobile or desktop version of your site, and select which categories you want to audit. When you’re ready, click Analyze page load.
5. Read your audit. This method will output your audit in the Chrome DevTools sidebar, which is really helpful if you want to use the Elements tab to see the code that the audit report is referencing.

3. Use Lighthouse With PageSpeed Insights

1. Go to PageSpeed Insights. Type “pagespeed.web.dev” into your browser’s URL bar. Unlike the two previous methods, this one works in any browser.
2. Enter your website’s URL. Then, click Analyze.

3. Wait for your audit. After a minute, your audit should appear. You’ll see tabs for Mobile and Desktop so you can compare how each version of your website performs.

Pro Tip: Lighthouse audits your website in a simulated environment, which gives us lab data. However, the PageSpeed Insights (PSI) method also gives us field data. This tool has access to real user data from the past 28 days, which you can find under the section titled “Discover what your real users are experiencing.” This may show varying data, but it gives a more holistic view of your website’s performance.

4. Use Lighthouse via a Node Module (Advanced)

If you’re a technically-minded user who’d prefer to work in the command-line and get the highest level of detail, I’d recommend this method.

1. Install Node. Go to “nodejs.org” and download the current Long-Term Support (LTS) release of Node. Then, open the installer and follow the steps – you don’t need to change any of the default settings.
2. Open your device’s CLI. This is Command Prompt on Windows or Terminal on macOS and Linux.
3. Install Lighthouse. In your CLI, type “npm install -g lighthouse” and wait until the packages are added.
4. Run an audit. Now, type “lighthouse”, followed by the URL you want to audit. At this point, your firewall may ask if you want to allow Node to run on your network. Click Allow.

5. You’re done! Unlike the other methods, the output of your audit will be displayed in the command line. However, it does provide more detail by showing the time in milliseconds it takes to load each element. This can be helpful to identify specific technical elements that are impacting performance.

Understanding Your Google Lighthouse Audit Results

Alright, so you’ve got your Lighthouse audit results, and you’ve probably already seen the four colored circles at the top of the audit that give you a general idea of your website’s health. It’s time to dive a little deeper.

Score Overviews and Breakdowns

As you saw earlier, we have 4 categories, each with an individual score. Let’s take a look at the Performance category, as this gives a really helpful breakdown of Google’s Core Web Vitals.

Your Performance score is calculated using the Core Web Vitals because they measure how well your page loads and how that impacts the user experience. Each metric is weighted, and you can get a rough estimate of how much each metric impacts the score by hovering over the overall score circle.

In this example, everything looks pretty healthy, but the LCP metric is showing some issues. This could indicate that the page is taking a while to load its largest chunk of content. Our page uses a lot of image-heavy sections, and it could be any of those that are causing the issue.

Fortunately, we don’t have to find the answer ourselves – let’s take a look at the Diagnostics list.

Under Diagnostics, we can see the majority of the current issues impacting our website’s performance. Click on any of the issues to expand them. I clicked on the issue relating to the high LCP metric, which gave me a handy link to a learning resource. I also got a more detailed breakdown of what’s taking more time to process.

Some issues also show you the specific code element that’s failing, giving you insight into exactly what you need to change.

Under this list, you can see your passed audits. I’d take note of these – that way, you know what’s already working and shouldn’t be tweaked further.

Critical Metrics

With so much information, how do you know what to pay attention to first?

First of all, look at the categories with a score below 50. Google Lighthouse scores below 50 indicate critical website issues, while scores between 50-89 indicate areas needing improvement.

If all your scores are similar, then you should address Google’s Core Web Vitals in the Performance category first. This category can directly impact the score you see for other categories, and it can help you uncover deeper issues with your website’s code and composition.

Otherwise, I recommend focusing on your lowest-scored category each audit, then retesting. This will help you to focus on the issues that matters most for your online presence. Plus, improving in one area may fix problems in another.

How To Fix Common Issues Highlighted by Lighthouse

While everyone’s Lighthouse audit will vary, there are common issues that can occur depending on how you set your website up.

If you’ve received a score that you’re not happy with, the first thing you should try is retesting. This can sometimes resolve a low performance score, particularly if your hosting provider or ISP network experienced a brief issue while you were testing.

If you’ve determined the problem is with your website, not your network or hosting server, then the following list outlines common issues and how to resolve them:

• Slow FCP. Your website’s CSS and JavaScript code could be slowing its loading speeds. Use our CSS and JS compressor to minimize file sizes and improve this metric.
• Slow LCP. This could be due to uncompressed web content files, which you can double-check with our GZIP/Brotli compression checker.
• High SI. If your site uses a lot of images, then it’ll take longer to load. Use an image compressor tool before you upload them to your media library to reduce the amount of bandwidth needed to load your page. You can also implement lazy loading techniques so off-screen images don’t impact your page load times.
• Poor mobile performance. Pages can sometimes have a high performance score on desktop, but a low one on mobile devices. Try our responsive design checker to make sure your website is loading correctly on mobile devices.
• Unused CSS. This indicates that there’s excess code that’s being loaded but not used. Tools like Chrome DevTools can help identify and remove this.
• Render-blocking resources. These can slow down your page’s loading speeds. Fix this by preventing non-critical code from loading while the page renders, so visible content is prioritized.
• Poor accessibility score. Common accessibility issues include low font sizes, poor color contrast, and no alt text on visual elements. Read our accessibility guide to learn how to fix these issues.
• Lack of HTTPS. Non-secured connections can impact trust and SEO rankings. Implement SSL certificates to ensure sitewide HTTPS.
• Poor SEO score. Ensure that you’ve set your website up so it can be indexed. Check that you’ve got a valid robots.txt file with our free tool.

Tips and Tricks for Using Google Lighthouse

To get the most out of Google Lighthouse, take a look at our list of community-sourced tips:

• Use Incognito mode. Running Lighthouse audits in Incognito mode can provide cleaner results by avoiding interference from browser extensions, which may skew your data. You could also try running audits on different browsers and devices to see if that affects your score.
• Take a median score. Your Lighthouse Performance scores can be affected by network conditions, your hosting provider, and even your own device’s performance. I recommend taking a median score of several audits as a baseline instead of relying on a single test.
• Run regular audits. Perform regular checks, especially after major updates to your chosen website or hosting platform. This can help you catch new issues early.
• Work on your knowledge. Google Lighthouse provides tons of resources for understanding Core Web Vitals and how to address issues. By familiarizing yourself with key scoring criteria, you can gain a new skillset, allowing you to better manage your site without paid assistance from others.
• Simulate slow connections. You can simulate throttling in Chrome DevTools, then run a Lighthouse audit to gauge how your website performs under different conditions. After all, your home network might be fast, but a user’s might not be!
• Run manual checks. Lighthouse is an automated testing tool, which means it can’t check for issues that can only be diagnosed with a visual overview of your website. You’ll get the most out of Lighthouse if you use it alongside regular manual testing.
• Aim for 90+. This will show as a green circle for the overall category score. It’s good to keep optimizing after this point, particularly if you’ve missed some best practices or have some loading issues. However, you may experience diminishing returns on your time spent.
• Analyze field data. Lighthouse only provides lab data, which doesn’t always reflect what real users experience. However, you can use PageSpeed Insights with
• Lighthouse to see this data. Alternatively, consider using a user experience testing platform to collect your own field data.

You Don’t Need To Be a Tech Genius To Use Lighthouse Tools

Designing a website that meets all of Google’s standards can be challenging. This task can be especially daunting due to the dynamic nature of these factors.

Fortunately, Google Lighthouse provides you with an easy method to test your website against crucial metrics. This assessment provides you with actionable insights aimed at enhancing your website’s performance, usability, and accessibility.

While it isn’t a comprehensive testing solution, it’s definitely an essential tool that all website managers should be using. Even if you’re not a tech wiz, you’ll find that you can still implement many of the necessary fixes yourself – and if you can’t, you’ll still know exactly what needs to be done and can reach out for assistance more effectively.

FAQs

Why do Lighthouse scores fluctuate between tests?

Lighthouse scores can fluctuate between tests due to a variety of factors, including changes in network conditions, server speed, visitor traffic, or even updates to the Lighthouse tool itself. I recommend taking a median score from several tests instead of relying on a single score.

Which metrics matter most for SEO?

All of your Lighthouse metrics will have an impact on SEO. However, if your SEO is suffering despite a good score in this category, start by looking at your Core Web Vitals under Performance. A slow-loading website can lead to lower search engine rankings as users will get frustrated and leave your website without interacting with more than one page.

Should I aim for 100 in all categories?

Aiming for a perfect score of 100 in all categories might seem ideal, but it isn’t always necessary or practical. Instead, focus on making meaningful improvements that enhance user experience and site performance. Remember, the goal is to continuously improve rather than to achieve perfection, as real-world constraints may limit your ability to reach top scores in every category.

How do I improve my Google Lighthouse score?

You can improve your Google Lighthouse score by resolving common performance issues. Start by optimizing images and compressing them to reduce load times. Leverage browser caching and minify CSS, JavaScript, and HTML to streamline your site. You should also ensure your site is mobile-friendly and accessible to all users, addressing any issues highlighted in the Accessibility and Best Practices categories.

How do I link my Wix site to Google Lighthouse?

Unlike other tools like Google Analytics, you don’t need to link a site to Google Lighthouse. To run a Lighthouse audit on your Wix site, all you need is its URL. Fortunately, all of Wix’s templates are already speed-optimized, and you get built-in SEO and accessibility tools to easily improve your Lighthouse scores further.