How to find the LCP element in PageSpeed Insights
Updated
Short answer
LCP measures how long it takes for the largest image, text block or other eligible element visible in the initial viewport to render. Start with one page in PageSpeed Insights. Use real-user data for the trend and the lab diagnostics to see what the test measured.
Enter a page visitors actually use
For a bakery, that might be the order page. Run its public URL in PageSpeed Insights and look at the mobile results. If real-user data is available, check whether it covers that URL or the whole origin. The good threshold is 2.5 seconds or less at the 75th percentile.
Find the element in the lab report
Look for the LCP breakdown in the diagnostics. If the test selected the large product photo, check whether the browser began fetching it late or spent a long time downloading it. When a block of text is selected, investigate what delays its rendering.
A published speed test
In Google Flights’ lab test, increasing the fetch priority of the main image reduced LCP from 2.6 to 1.9 seconds.
Keep one change easy to check
Save the URL, device, LCP element and longest phase. Test the same page under similar conditions after changing one thing. The lab run is useful for diagnosis, and field data reflects a rolling 28-day window of real visits.