One SEO professional asked John Mueller during a hangout about their page speed numbers. More specifically, their PageSpeed insights score.
They explained that when they check the PageSpeed Insights score on their website, they see a simple number.
Why doesn’t this number match what they see in Search Console and the Core Web Vitals report?
Which of these numbers are correct?
John Mueller explained that first of all, there is no correct number when it comes to speed, when it comes to understanding how your website is performing for your users.
In PageSpeed Insights by default, John believes that they show a single number that is a score from zero to 100.
This is based on a number of assumptions, where they assume that different things are a little bit faster or slower for users.
Based on that, they calculate your score in PageSpeed Insights.
In Search Console, Google has the Core Web Vitals information, which is based on three numbers for speed, responsiveness, and interactivity.
These numbers are slightly different, of course, because it’s just three numbers and not just one number.
Also, there’s a big difference in the way that these numbers are determined. Namely, there’s a difference between so-called field data, and the lab data.
Field data is what users have seen when they actually visit the website. This is what Google uses in Search Console, and that’s what they use for search also.
Lab data, however, is a theoretical view of your site, in which Google’s systems make certain assumptions about the user, their device, and their internet connection. For example, they may think: perhaps the average user is using this kind of device or even a certain type of connection.
Based on these assumptions, Google will estimate what the numbers might be for an average user.
Obviously, you can imagine that these estimates will never be 100 percent correct.
Similarly, the data that users have seen will change over time also, because some users may have a really fast connection or a fast device, and everything goes fast on their website.
And others might not have this same experience.
Because of that, this variation can always result in different numbers.
Google’s recommendation is generally to use field data, the data you see in Google Search Console, as a way of understanding what is the current situation for your website.
Then, use the lab data, namely the individual tests that you can run directly yourself, to optimize your site and try to improve things.
When you are pretty happy with the lab data that you’re getting with your new version of your site, then over time, you can collect field data, which happens automatically.
Using this field data, you can double check that users actually see your site as being faster or more responsive as well.
Again, there is no absolutely correct number. Rather, there are different assumptions and different ways of collecting this kind of data.
This happens at approximately the 00:45 mark in the video.