PageSpeed Insights
- A free tool from Google, at pagespeed.web.dev, that tests how fast a web page loads on a phone and on a computer and gives it a score out of 100, with a list of things to improve.
- Scores of 90 to 100 are green (good), 50 to 89 are amber and anything below 50 is red. The report has two parts: data from real Chrome visitors, which appears only for sites with enough traffic, and a lab test that Google runs on the spot, which is what produces the score. Lab results vary a little each time, and the mobile test deliberately simulates a slower phone and connection, so judge by the colour band and the trend rather than by one number.
Example The report flagged the homepage photos as the biggest saving, so they were converted to WebP.
The four scores
The report gives four separate scores: Performance (speed), Accessibility, Best Practices and SEO. Performance is the one that depends on Core Web Vitals. The others check for good practice, such as readable text, a secure connection and pages that search engines can read. All four use the same colour bands.
What to look at first
The list of suggestions under the scores is more useful than the number at the top. The biggest items are usually oversized images (see WebP), scripts and styles that block the page from showing, and fonts that load late. Each suggestion shows the estimated saving, so you can start with the largest and ignore the tiny ones.
Common questions
Why is my mobile score lower than my desktop score? The mobile test pretends to be a slower phone on a slower connection, so the same page always scores lower there. That is deliberate, because many visitors really are on phones.
Do I need 100? No. Once you are in the green, further gains are small and rarely noticeable to visitors. How the site feels to real people matters more than the last few points.
Why does it say “No data”? The real-visitor section needs enough Chrome users to have visited the page recently. New or small sites often do not have that yet, and the lab test underneath still works.
See also Core Web Vitals WebP Caching