Core Web Vitals
Web PerformanceDefinition
Core Web Vitals are a set of three Google metrics that measure real-world page experience: loading speed (LCP), responsiveness to input (INP) and visual stability (CLS). They quantify how fast a page feels and how stable it is for actual users, and Google uses them as a ranking signal and as a proxy for landing page quality.
Core Web Vitals break page experience into three measurable parts. Largest Contentful Paint (LCP) measures how long it takes for the main content to appear, with a good score under 2.5 seconds. Interaction to Next Paint (INP), which replaced First Input Delay in 2024, measures how quickly the page responds when a user taps or clicks, with good responsiveness under 200 milliseconds. Cumulative Layout Shift (CLS) measures how much the layout jumps around as it loads, with a good score under 0.1. Together they describe whether a page feels fast, responsive and stable to a real person on a real device.
Crucially, these are field metrics, not just lab scores. Google reports them based on real Chrome user data, so a page that looks fast on your developer machine can still fail if mobile users on slower connections have a poor experience. Lab tools like Lighthouse help you diagnose causes, but the scores Google acts on come from actual visits. That distinction matters because the most common fixes, oversized images, render-blocking scripts, slow servers, unsized media that pushes content around, only show their full effect once real users feel them.
Google collects Core Web Vitals from real Chrome users in the Chrome User Experience Report and exposes them in Google Search Console and PageSpeed Insights. A page is assessed at the 75th percentile of visits, so it needs to be fast for most users, not just on average. To improve, you optimise the largest element for quick rendering (LCP), reduce heavy JavaScript and long tasks so interactions feel instant (INP), and reserve space for images, ads and embeds so nothing shifts as it loads (CLS).
Core Web Vitals matter on two fronts. They are a confirmed, if modest, organic ranking factor, and more importantly they shape conversion rate: slow, janky pages lose visitors before they convert, which directly raises your effective cost per acquisition. For paid traffic the link is just as real, since landing page experience feeds into Google Ads Quality Score, and a faster, more stable page can lower CPCs and lift conversions on the exact traffic you are already paying for. Speed is not a vanity metric; it is money.
Example
An ecommerce product page has an LCP of 4.1 seconds because of an uncompressed hero image and a slow server response. Mobile bounce rate is high and the page fails Core Web Vitals. After compressing the image, adding a CDN and reserving image dimensions, LCP drops to 1.9 seconds, CLS falls below 0.1, and conversion rate on mobile climbs measurably.
On paid traffic, the same fix improves landing page experience in Quality Score. A page that moves from a slow to a fast Core Web Vitals profile can shave a meaningful slice off CPC, so the budget you already spend buys more clicks and more conversions.
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Frequently Asked Questions
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Largest Contentful Paint (LCP) measures loading speed, good under 2.5 seconds. Interaction to Next Paint (INP) measures responsiveness, good under 200 milliseconds, and replaced First Input Delay in 2024. Cumulative Layout Shift (CLS) measures visual stability, good under 0.1. Together they describe how fast, responsive and stable a page feels to real users.
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Yes, but modestly. They are a confirmed ranking signal as part of page experience, though relevance and content quality still matter more. The bigger reason to care is conversions: faster, more stable pages keep more visitors and turn more of them into customers, which benefits both organic and paid traffic.
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Landing page experience is a component of Quality Score, and Core Web Vitals are a large part of that experience. A faster, more stable page tends to earn a higher Quality Score, which can lower your CPC and improve ad position. In short, fixing them often makes your existing ad budget go further.
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