What is measured
The audit compares laboratory LCP with the 2.5-second good threshold and stores milliseconds for repeat testing.
Performance and mobile experience
Largest Contentful Paint (LCP)
This check measures when the largest visible content element appears in the viewport.
Pass criterion
The main heading, image or other LCP element consistently appears within the good threshold.
What to fix
Identify the actual LCP element and improve its resource, priority, server response and critical styles.
Automation limit
Laboratory LCP is a control scenario; final assessment also needs field data from real users.
Reference