LCP
Data & TrackingAlso: Largest Contentful Paint · Core Web Vital LCP
Quick definition
One of Google's Core Web Vitals — measures how long it takes for the largest visible element on a page (typically an image or headline) to load and render for the user.
Where it shows up in the data
LCP measures the time until the largest element in the viewport (visible screen area) finishes rendering. This is typically a hero image, a heading text block or a video thumbnail. It is a proxy for 'when does this page feel loaded?'
Images (img, image in CSS background), video poster frames, block-level text elements and SVGs can all be the LCP element. The largest in the viewport wins. Identifying your LCP element is the first step to optimising it.
LCP is one of three Core Web Vitals used by Google as a page experience ranking signal. The others are INP (Interaction to Next Paint, which replaced FID) and CLS (Cumulative Layout Shift). Collectively they measure loading, interactivity and visual stability.
LCP can be measured in lab conditions (simulated, e.g. Google Lighthouse) or from real users (field data via Chrome User Experience Report / CrUX). Google's ranking uses real user data. Lab data is useful for debugging but may not match real-world performance.
What it actually means
LCP (Largest Contentful Paint) measures how quickly the most prominent visual element on a page loads and paints to the screen. It is a user-centric metric because it captures the moment when the page feels usable rather than just when the HTML starts loading. A low LCP means visitors see your content quickly. A high LCP means they sit waiting on a partially loaded page, which is a conversion killer. Google uses LCP as a direct ranking factor as part of its Core Web Vitals assessment.
LCP is not a technical metric. It is a measure of how long you make visitors wait before they can trust your page is working.
How to calculate it
LCP is measured in milliseconds from the start of the page load (navigationStart) to when the largest contentful element finishes rendering. Good: < 2500ms. Needs improvement: 2500-4000ms. Poor: > 4000ms.
Worked example. A page's hero image takes 3.8 seconds to load and render. LCP = 3.8 seconds. This falls in the 'Needs Improvement' range. Compressing the image and adding preload hints brings it to 2.1 seconds — 'Good'.
The Australian context
Australian web hosting and CDN configuration significantly affects LCP for Australian visitors. Sites hosted on US-only servers without a CDN (Content Delivery Network) serving Australian edge nodes will have higher LCP for Australian users. Use PageSpeed Insights with a location parameter to check Australian user experience specifically.
Where people get this wrong
Related terms
Common questions
How do I find my LCP score?
Three ways: (1) Google PageSpeed Insights (pagespeed.web.dev) — paste your URL for a quick lab measurement. (2) Google Search Console > Core Web Vitals report — shows real user data. (3) Chrome DevTools Performance tab — shows the LCP element and timing in detail.
What causes slow LCP?
The most common causes: large uncompressed images, render-blocking JavaScript or CSS, slow server response time (TTFB), no CDN for geographically distant servers, and third-party scripts loading before the LCP element.
Does LCP affect Google rankings?
Yes. LCP is one of three Core Web Vitals that Google uses as a ranking signal in its Page Experience update. Sites with 'Good' LCP receive a small but real ranking boost over sites with 'Poor' LCP, all else being equal.
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About New Rebellion
New Rebellion is a marketing intelligence consultancy. We build tools, score Australian businesses on how their marketing actually performs, and publish Debrief every day. This dictionary is part of how we work in the open.
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