Core Web Vitals
Core Web Vitals are the performance signals that define how users experience your site. They are measured and enforced by Google. Poor scores suppress rankings and reduce conversion rates simultaneously. Improving them requires addressing root causes, not chasing score metrics.
Google’s Core Web Vitals measure three dimensions of page experience: how fast the main content loads (LCP), how visually stable the page is during load (CLS), and how quickly the page responds to user input (INP). These signals are collected from real Chrome users and fed into Google’s Page Experience ranking system.
The relationship between CWV and rankings is real but nuanced. Vitals are a tiebreaker signal for pages with otherwise similar ranking factors. For sites competing in medium to high-competition queries, poor CWV performance is a disadvantage that compounds over time as competitors improve their scores. For sites with technical debt, fixing CWV often uncovers and resolves broader performance problems that affect user engagement metrics independently of search rankings.
| Metric | Value | Change | What it means |
|---|---|---|---|
| LCP (Largest Contentful Paint) | Good: under 2.5s | Target | How fast the main content element loads. Affected by server response, render-blocking resources, and image optimization. |
| CLS (Cumulative Layout Shift) | Good: under 0.1 | Target | Visual stability during load. Caused by images without dimensions, web fonts shifting layout, and late-loading dynamic content. |
| INP (Interaction to Next Paint) | Good: under 200ms | Target | Responsiveness to user input. Affected by JavaScript execution, heavy event handlers, and main thread blocking. |
Common root causes
LCP: what actually causes slow loading
LCP is commonly blamed on image size, but the root cause is often earlier in the load sequence: slow Time to First Byte from server or CDN configuration, render-blocking CSS or JavaScript that delays the browser from rendering the largest element, or a large background image loaded via CSS that cannot be preloaded. We identify the actual bottleneck for each page type rather than applying generic optimizations.
CLS: why layouts shift
Layout shift typically comes from images and iframes without defined width and height attributes (the browser cannot reserve space before they load), web fonts that load after initial text rendering causing a reflow, and dynamically injected content (banners, cookie notices, ads) inserted above existing content. See web.dev’s CLS documentation for the full measurement model.
INP: interaction delays
INP replaced FID as the interaction metric in 2024. It measures the latency of all user interactions during a page session. Heavy JavaScript event handlers, long tasks on the main thread, and frameworks that defer interaction handling all contribute to poor INP. This is particularly common on sites built with heavy page builders or plugin-heavy WordPress installations. See our WordPress SEO service for platform-specific fixes.
Google uses field data from the Chrome User Experience Report (CrUX) for ranking decisions, not lab data from Lighthouse. A Lighthouse score of 90 does not guarantee good field data if real users on slower connections or older devices have poor experiences. We measure both and prioritize fixing what affects real user data.
Related services
Frequently asked questions
Yes, but as a tiebreaker signal rather than a primary ranking factor. Google has confirmed that CWV are part of the Page Experience ranking signal. Sites that score poorly on CWV are at a disadvantage when competing against pages with similar content quality and authority. For highly competitive queries, poor CWV performance is a measurable disadvantage.
Google Search Console provides field data (real user data) for CWV across your pages. PageSpeed Insights provides both field data and lab data for individual URLs. The Chrome DevTools Performance panel and Lighthouse provide lab data for debugging. For ranking purposes, field data from Search Console is the most relevant because it reflects what Google actually uses.
Lighthouse is a lab test run on a simulated connection and device. Search Console shows field data from real Chrome users on real devices and connections. Real users may be on slower connections, older devices, or visiting pages with more dynamic content loaded than the Lighthouse test captures. Always prioritize Search Console field data for ranking-related decisions.
Yes, if its content and authority signals are significantly stronger than competing pages. CWV is a tiebreaker, not a hard filter. However, as more sites improve their performance scores, the competitive gap created by poor CWV grows. Sites that have not addressed CWV are increasingly at a disadvantage in queries where competing pages have comparable content quality.