Why the SEO “Mobile Speed” score and Google PageSpeed score are different

We use the Lighthouse API to perform the mobile speed checks in SEO. 

There can be a discrepancy between the mobile speed displayed on the platform and the speed shown when using Google PageSpeed. The reasons for this are data type and measurement locations as described below. 

Data type

Google PageSpeed uses both real-world data available in the Chrome User Experience report and lab data.

Google Lighthouse uses lab data only to measure your website’s performance

•    Lab data = simulated data

•    Real-world data = actual data

Measurement location

Another factor affecting the results is that the default settings for the location from where checks are performed might be different.

For example, when you’re using PageSpeedInsights and run it from the browser, it chooses the location closest to you. With Lighthouse API, the locations may not be the same.