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How to Read a Lighthouse Report

Lighthouse is an automated tool that audits web pages for performance, accessibility, best practices, and SEO.
lighthouse report

Lighthouse is a powerful open-source tool that helps web developers optimise their website’s performance, accessibility, and more. If you’re a website owner or developer, you’ve likely heard of Lighthouse and its importance in ensuring a smooth user experience. However, understanding how to read a Lighthouse report can be challenging.


In this post, we’ll break down the critical components of a Lighthouse report, what each section means, and how to use the information to improve your website’s performance.

What is Lighthouse and How Does it Work?

Lighthouse is an automated tool that audits web pages for performance, accessibility, best practices, and SEO. It’s built into Google Chrome and can be accessed through the browser’s DevTools.


It simulates how a website loads and performs on a user’s device and then generates a report with recommendations on improving the website’s performance.


Lighthouse will provide one score for desktop and another for mobile, so it’s essential to look at both and optimise your performance as needed.

What are the 5 Audit Categories in Lighthouse?

When you run a Lighthouse report, it generates a score for each of the five audit categories: Performance, Accessibility, Best Practices, SEO, and Progressive Web App (PWA). Each category is scored on a scale of 0 to 100. A higher score indicates better performance and adherence to best practices.



This measures how fast your website loads and performs. It evaluates metrics such as First Contentful Paint, Speed Index, Time to Interactive, and more.



This category checks your website’s accessibility for users with disabilities. It checks for proper alt text for images, keyboard navigation, and colour contrast.


Best Practices:

Evaluates your website’s adherence to web development best practices. It checks for things like properly using HTML and CSS, avoiding deprecated code, and ensuring secure connections.



This allows you to look at your website’s search engine optimisation. It checks for things like metadata, headings, and structured data.


Progressive Web App (PWA):

This tests your website’s ability to function like a native app on a mobile device. It checks for proper use of service workers, offline support, and a manifest file.

What Does a Good Score on Lighthouse Mean?

A good score on Lighthouse means your website is performing well and adhering to best practices. However, it’s important to note that a high score doesn’t guarantee a perfect website or high rankings on SERPs. There will still be areas where your website can improve elsewhere in Lighthouse, such as user experience or content quality.


Additionally, it’s essential to understand how these scores relate to your website’s goals and audience. A score of 60 in one category may be acceptable for a small business website, while a score of 95 may be necessary for a large e-commerce site with high traffic.


While we do use Lighthouse score in our audits, we suggest focusing on good user experience rather than placing all your emphasis on getting a perfect score.

How do I use a Lighthouse Report?

To understand a report, it’s necessary to know what each section means and how to interpret the information.


Start running a Lighthouse report on your website using Google Chrome’s DevTools.


To open the DevTools in Google Chrome, open the Chrome Menu in the upper-right-hand corner of the browser window and select More Tools > Developer Tools.


Once the report is generated, you’ll see a breakdown of the five audit categories with a score for each.


Take the time to review each section of the report and identify areas where your website can improve. Focus on the areas with the lowest scores that are more likely to significantly impact UX and crawlability, and consider the recommendations provided by Lighthouse.


For example, if your website has a low score in the Accessibility category, Lighthouse may suggest adding alt text to images or improving keyboard navigation. Implementing these recommendations can help improve your website’s accessibility and overall user experience.


Running regular reports regularly is vital to track your website’s progress. Run another report to see if your scores have improved as you make improvements. This can help you identify areas that still need work and ensure your website is continuously optimised.

Do Lighthouse Scores Affect SEO?

When discussing Lighthouse, one question is whether the scores affect your website’s SEO.


The short answer is it depends (sorry, we had to). While Lighthouse scores are not a direct ranking factor for search engines like Google, they can indirectly impact your website’s search engine rankings.


A website with a high Lighthouse score will likely perform better regarding page speed, accessibility, and other vital factors that search engines consider when ranking websites. However, they will not perform better just because they have a higher score.


Lighthouse also provides recommendations for improving your website’s SEO, such as adding metadata and improving structured data.


Implementing these recommendations can improve your website’s search engine rankings over time.

How can I Benefit from using Lighthouse Scores?

Reading a Lighthouse report may seem daunting at first, but with some understanding, you can use the information to improve your website’s performance, accessibility, and more.


By focusing on the areas with the biggest opportunity and implementing Lighthouse’s recommendations, you can optimise your website for better overall performance.


Remember, these scores are relative to your website’s goals and audience, so it’s essential to consider those factors when interpreting the results.


Using Lighthouse can help you stay on top of your website’s performance and continuously improve.

Picture of Nikki Halliwell

Nikki Halliwell

Based in Manchester, UK, Nikki is a freelance Technical SEO Consultant. She has worked at several agencies and in-house and has worked across the health, hospitality and fashion industries and more. Nikki enjoys working with eCommerce websites and beyond to ensure that websites are easy to find, load quickly and work efficiently.