What is Goole lighthouse and how to improve your score

The 5 areas are;

  1. Performance
  2. Progressive web app
  3. Accessibility 
  4. Best Practices
  5. SEO 

Lighthouse will rate each section out of 100, using a colour system to define how the website ranks in each section. 0-49 being red meaning poor quality, 50-89 meaning it could be improved and 90-100 being a green aiming which is what you should be aiming for. 

You can use Lighthouse as a Google Chrome extension or with Chrome DevTools. 

The best way to advise people on how to optimise a site for Google lighthouse is to breakdown the 5 sections and define what they mean and how your site can improve its rating in that section. 


The performance audit is broken up into several different loading points that all impact websites overall ranking. Lighthouse will load a web page commonly in 7 steps until it is fully loaded. It is worth noting if you see a 0 score repeatedly you should file a bug on the lighthouse repo. Reducing server response time, having properly sized images and deferring offscreen images are all ways you can improve your performance score. Different points of the performance test are weighted differently in terms of score. 

After you run a performance audit, Google lighthouse will present you opportunities on how to improve your page load time. Following these can get you closer to the goal score of 100. 

Progressive Web App 

The progressive web app score is based on the “baseline progressive web app checklist” which is provided by Google. Unlike the performance scoring, all the factors of the progressive web app are weighted the same in terms of score. Lighthouse automatically audits 11 of the 14 requirements with the other 3 needed to be tested manually. Following Googles checklist can lead to a perfect score on the progressive web app element to Lighthouse.


The accessibility audit is pass or fail, unlike performance audit where a page gets points for partially passing. 

The main goal of the accessibility test is to score how clear your website’s content is presented to visitors. These include users who may use assistive technology. It’s important that your site is accessible to all website users as Google Lighthouse make this a high priority. To score high in accessibility make sure your website is clearly described and well-structured. 

Best Practices 

Following best Google’s practices is a rule web developers and marketers should always follow as it can cause major issues down the line. Implementing the best practises while designing a website can prevent future problems for the site.  


Google lighthouse looks at nine basics of search engine optimisation. These are currently designed to ensure the website reflects the SEO basics that every website should have. The google scoring guide has details of how each section is broken down and what Google wants to see from your website.