Lighthouse performs an analysis by running your web page against standard metrics and rules for each selected category. It then calculates an overall score between 0 and 100 that indicates how well your web page performs. Lighthouse uses the axe-core library to power its accessibility score.

Once the Lighthouse tool opens, ensure all five categories are selected, then (2) choose Generate report. You'll find a score and section for each category. You can learn more about each by clicking on the scores at the top of the page. A good score is considered anything between 50 and 89.

Google's Lighthouse tool tests the performance of a website and gives it a score rating from 0 to 100. This Performance score is calculated by combining several different performance metrics. The Performance rating that's shown on PageSpeed Insights is also calculated using Lighthouse.

To provide a good user experience, sites should strive to have a good score (90-100). A "perfect" score of 100 is extremely challenging to achieve and not expected. For example, taking a score from 99 to 100 needs about the same amount of metric improvement that would take a 90 to 94.