CORE WEB VITALS & PERFORMANCE
Largest Contentful Paint: what it means and how it works
When the main image or text block appears; good is 2.5 seconds or less.
- Intermediate level
- 2 primary sources
- Reviewed 29 October 2026
- TopicCore Web Vitals & performance
- LevelIntermediateAssumes the basics of how search works
- Also calledLCP
- Sources2 primary sourcesweb.dev
- Reviewed29 October 2026Re-checked every 12 months
On this page
Quick definition
Largest Contentful Paint (LCP) is the time from when a page starts loading until its largest image or text block in the viewport is displayed. It is the Core Web Vital for loading; 2.5 seconds or less at the 75th percentile is good.
How it works
The browser reports the largest element rendered in the viewport as the page loads: an image, a video’s poster image, an element with a CSS background image, or a block of text. The last candidate before the user interacts is the LCP element.
| Part of LCP | What happens | Common cause of delay |
|---|---|---|
| Time to First Byte | Waiting for the HTML | Slow server, no caching, redirects |
| Resource load delay | Time before the browser starts fetching the LCP image | Image found late: lazy-loaded, set by JavaScript or CSS |
| Resource load duration | Downloading the image | Oversized or unoptimised image |
| Element render delay | Time until it is painted | Render-blocking CSS and scripts, client-side rendering |
Example
A property portal’s listing pages have a mobile LCP of 4.6 seconds. The LCP element is the main photo, a 2.4 MB JPEG loaded by a slider script, with loading="lazy". Serving a correctly sized WebP, removing lazy loading from the first photo and adding fetchpriority="high" lets the browser fetch it immediately.
How to check it
- Find the LCP element in PageSpeed Insights or the browser’s performance panel.
- Check whether the LCP image is in the initial HTML, not lazy-loaded, and appropriately sized.
- Measure Time to First Byte; if it is slow, start there.
- Confirm improvements in field data over the following 28 days.
Common mistakes and misconceptions
Myth LCP measures when the whole page finishes loading.
In fact It measures when the largest visible element appears, which can happen long before the page fully loads.
Myth Lazy-loading every image always helps.
In fact Lazy-loading the main above-the-fold image delays LCP.
Check it on your site
Free tools, no sign-up
- FreeCore Web Vitals CheckerCheck a page’s real-user LCP, INP and CLS from the Chrome UX Report, for the page and its whole site.Open the tool
- FreeImage File & Optimization InspectorCheck the images on a page: file size, format, caching, width and height, lazy loading and responsive sources.Open the tool
In the NdovuSEOLabs platform
Run the same checks on every page of your site, with your own data.
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Sources and review
- Largest Contentful Paint (LCP) web.dev
- Optimize Largest Contentful Paint web.dev
Written and maintained by Ndovu SEO Labs. First published 29 October 2026. Facts last checked against the sources above on 29 October 2026. How we write and review the glossary.