URL: /glossary/lcp --- title: "What is LCP? Largest Contentful Paint and its causes" description: "LCP is the time until the largest image, text block or video in the viewport renders. Good is 2.5 seconds. Its causes, and the hints squirrelscan checks." sidebarTitle: "Largest Contentful Paint (LCP)" --- **Largest Contentful Paint (LCP)** is the time from the start of a page load until the largest image, text block or video visible in the viewport has rendered. It is the loading metric of the [Core Web Vitals](/glossary/core-web-vitals). web.dev counts 2.5 seconds or less as good and more than 4 seconds as poor, judged at the 75th percentile of page loads. Its optimization guide splits LCP into four parts that add up to the whole: time to first byte, resource load delay (until the browser starts fetching the LCP resource), resource load duration and element render delay. {/* glossary:hub:start */} Category: [Performance](/rules/perf) {/* glossary:hub:end */} ## Why it matters On most pages the LCP element is an image, and most of what delays it is in the markup. A hero the preload scanner cannot find starts late. One marked `loading="lazy"` waits for layout before it is requested at all. Stylesheets and scripts in `` hold up the first paint, and a slow server response pushes everything back, because nothing paints before the HTML arrives. web.dev also warns that shrinking the image alone can just move the saved time into render delay. ## How squirrelscan checks it squirrelscan does not measure LCP. A crawl has no paint timing, so the rules look for the causes instead. [perf/lcp-hints](/rules/perf/lcp-hints) and [perf/lcp-fetchpriority](/rules/perf/lcp-fetchpriority) pick the likely hero from the first eligible images in document order, skipping lazy images, SVG and ICO files, tracking pixels, images inside `
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