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1Repair Windows errors before they cause bigger problems2Fix the driver behind crashes, sound loss and screen glitches3Clear out junk files and repair common Windows errorsCore Web Vitals are three field metrics that describe how quickly a page’s main content loads, how promptly it responds to interaction, and whether its visible content stays stable. Google’s current “good” targets are LCP within 2.5 seconds, INP under 200 milliseconds, and CLS under 0.1. Marketers can use them to find and prioritize user-experience problems—but they are not a standalone SEO score, and passing them does not guarantee higher rankings.
What Core Web Vitals measure
The three metrics describe different parts of a visitor’s experience. They are not interchangeable: a page can load its main content quickly yet respond slowly to taps, or respond quickly while elements jump around as it loads.
| Metric | What it measures | Google’s “good” target |
|---|---|---|
| Largest Contentful Paint (LCP) | Loading performance: when the page’s main content has likely loaded. | Within 2.5 seconds |
| Interaction to Next Paint (INP) | Responsiveness: how quickly the page responds visually to user interactions. | Under 200 milliseconds |
| Cumulative Layout Shift (CLS) | Visual stability: unexpected movement of visible page content. | Under 0.1 |
These are Google’s current target thresholds, not a promise that every visit will produce the same result. Google recommends assessing performance at the 75th percentile: in practical terms, the target should be met for at least 75% of measured page visits. Where data allows, check mobile and desktop separately because the experience can differ by device. Google Search Central’s Core Web Vitals guidance and web.dev’s Web Vitals overview explain the targets and assessment approach.
How to interpret the numbers
LCP: loading the main content
LCP focuses on when the largest visible content element has appeared, which is often a useful proxy for when the page feels meaningfully loaded. A slow LCP points to a loading experience to investigate; it does not, by itself, identify the technical cause.
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INP: responsiveness after an interaction
INP reflects how quickly a page provides a visual response across user interactions. It replaced First Input Delay (FID) as a Core Web Vital on March 12, 2024. FID is historical context, not the current responsiveness metric. web.dev’s announcement of the change documents the transition.
CLS: unexpected movement
CLS captures unexpected movement of visible content. A higher value indicates less visual stability; the target is below 0.1. Treat a poor CLS result as a signal to examine what is shifting rather than as a diagnosis of the cause.
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Field data and lab tests answer different questions
Core Web Vitals are field metrics: they reflect real visits, where device capabilities, network conditions, other processes, and the way visitors use a page can all affect results. That makes field data useful for understanding the experience people actually encounter, but also means results can vary.
Lab tests run under controlled conditions and help diagnose performance issues. They are useful for investigation, but should not be treated as a substitute for field measurement. As web.dev puts it, “While lab measurement is an essential part of delivering great experiences, it is not a substitute for field measurement.”
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Where marketers can check Core Web Vitals
Start with Google’s reporting and diagnostic tools. The right tool depends on whether you need a view across pages, an individual-page check, or a closer technical investigation.
- Search Console Core Web Vitals report: Review grouped field-data issues across the site and identify page groups that need attention.
- PageSpeed Insights: Check a URL for Lighthouse lab diagnostics and, when enough real-user data exists, Chrome User Experience Report (CrUX) field data. Field data may be page-level or origin-level; if a page lacks enough samples, the report may fall back to origin-level data. In some cases there is not enough data for an assessment. See Google’s PageSpeed Insights documentation.
- Chrome DevTools: Investigate page behavior during development and testing. Google lists it among the available ways to measure or investigate these metrics.
- web-vitals JavaScript library: Use it when your technical team wants to collect or monitor metrics in a site’s own measurement setup. Google lists the library as an official measurement option.
For a useful comparison, keep the page or page group consistent over time and separate mobile from desktop where the report provides that breakdown. This makes it easier to tell whether an observed change reflects a particular experience rather than a shift in what is being compared. A reporting or monitoring service may help teams track results, but Google’s official tools are valid starting points; a paid product is not required.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How Core Web Vitals relate to Google Search rankings
Google says Core Web Vitals are used by its ranking systems, but good scores do not guarantee top rankings. Page experience is broader than these three metrics: Google also points to factors such as security, mobile usability, intrusive interstitials, and distracting ads, while its systems seek relevant content. Google describes many page-experience assessments as page-level, while some are site-wide. Its guidance is explicit: “There is no single signal.”
A careful way to explain the relationship to a team is: Core Web Vitals are part of Google’s page-experience considerations and a useful way to identify user-experience problems. Passing the reports does not guarantee a ranking increase; relevance and the broader page experience still matter. Read Google Search Central’s “Understanding Google Page Experience” for its explanation.
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