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Performance

Largest Contentful Paint (LCP)

Published: · Updated:

Largest Contentful Paint (LCP) measures the time from the start of navigation until the largest content element in the viewport is rendered — most often a hero image, video or large block of text. It is the primary metric of perceived loading speed and one of the three Core Web Vitals.

Google considers a score up to 2.5 seconds good, between 2.5 and 4 seconds in need of improvement, and above 4 seconds poor — measured at the 75th percentile of real visits.

What LCP is made of

  • TTFB — time to the first byte of the server response.
  • Resource load delay — the gap between the HTML response and the start of the LCP resource download.
  • Resource load time — downloading the image or other file.
  • Render delay — time until the element is actually painted on screen.

How to improve LCP

The most effective actions are: reducing TTFB (caching, CDN), prioritizing the LCP resource (fetchpriority="high", preload), eliminating render-blocking CSS/JS, and optimizing images (modern formats, correct dimensions, no lazy loading on the LCP element).

Example

A hero image as the LCP element — preload and fetchpriority="high" reduce resource load delay. Do not use loading="lazy" on the LCP element.

Preload in <head>
HTML 
<link rel="preload" as="image" href="/hero.webp" type="image/webp">
Hero image with priority
HTML 
<img src="/hero.webp" alt="Product in use"
     width="1200" height="630" fetchpriority="high">

Sources & further reading

Related terms

Core Web Vitals A set of three Google metrics (LCP, INP, CLS) measuring loading speed, interaction responsiveness and visual stability of a page under real-world conditions.Time to First Byte (TTFB) The time from sending a request until the first byte of the server response arrives. The foundation of a fast LCP; a good score is roughly ≤ 800 ms.Cumulative Layout Shift (CLS) A Core Web Vitals metric measuring visual stability — the sum of unexpected layout shifts on a page. A good score is ≤ 0.1.Interaction to Next Paint (INP) A Core Web Vitals metric measuring the latency between a user interaction (click, tap, key press) and the next screen paint. A good score is ≤ 200 ms.
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