LCP: definition
LCP, Largest Contentful Paint, measures the time needed to display the largest visible element of a page on screen.
What LCP measures and why it matters
On an online store, the element counted as the LCP is very often a product page's main image or a featured visual on the homepage. Google measures the time elapsed between the start of loading and the moment this element becomes fully visible on screen, not just when the HTML is received.
A slow LCP gives visitors the impression that the site is taking a long time to display, even if other elements are already visible. Google rates an LCP under 2.5 seconds as good, between 2.5 and 4 seconds as needing improvement, and beyond that as poor. On a product page, a degraded LCP is often explained by an image that's too heavy, a lack of preloading, or an already high server response time.
Unlike TTFB, LCP also depends on the weight of resources and the loading order of CSS and JavaScript.
Frequently asked questions
Can LCP relate to text rather than an image?
Can lazy loading make LCP worse?
Is LCP the same on every page of a store?
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