Core Web Vitals
Core Web Vitals are Google's three user-experience metrics for a page's loading speed, interactivity, and visual stability: LCP, INP, and CLS.
- Also called
- CWV, Google Core Web Vitals
- Applies to
- Web pages, user experience metrics
- Commonly confused with
- PageSpeed score, single ranking factor, lab test results
Key points
- Core Web Vitals consist of three separate metrics: LCP, INP, and CLS.
- INP replaced FID as the Core Web Vital in March 2024.
- Each metric has a specific threshold: LCP ≤ 2.5 seconds, INP < 200 ms, CLS < 0.1.
- Optimise the weakest metric first, because a page can pass or fail each metric individually.
- Good Core Web Vitals are part of page experience signals but do not compensate for weak content.
How it works
Core Web Vitals measure real-world user experience using field data from the Chrome User Experience Report. The three metrics target different aspects of page interaction: loading speed (LCP), responsiveness (INP), and visual stability (CLS).
Largest Contentful Paint (LCP) records the time it takes for the largest visible element to render. Google recommends keeping LCP at 2.5 seconds or less. Interaction to Next Paint (INP) evaluates how quickly a page responds to user interactions such as clicks and taps; the recommended threshold is under 200 milliseconds. Cumulative Layout Shift (CLS) measures unexpected movement of page elements during loading, with a recommended score below 0.1.
These metrics are collected from real users, not synthetic lab tests, so they reflect actual conditions like device type, network speed, and browser behaviour. Lab tools such as PageSpeed Insights can estimate values, but site owners should rely on field data from Google Search Console for accurate assessment. For a deeper analysis of how these metrics fit into a broader technical review, a professional seo audit should include a breakdown of each metric.
Why it matters
Core Web Vitals are part of Google's page experience signals, which influence search performance. While they are not a direct ranking factor in isolation, they can affect a page's visibility when real-world user experience is poor. For SEO practitioners, they serve as a practical diagnostic: a slow LCP, high INP, or large CLS points to specific technical issues that degrade user satisfaction and may lead to lower organic traffic.
Improving these metrics often correlates with better engagement, lower bounce rates, and higher conversion rates. However, the impact on rankings is limited compared to content relevance and backlinks. A site that optimises its core web vitals seo signals but ignores content quality will not see a significant ranking boost.
Where it changes your decision
- When deciding which technical issues to fix first: target the metric that is failing its threshold, because each metric is independent and optimising the weakest yields the most improvement.
- When evaluating a site's user experience during a redesign: use Core Web Vitals field data to set performance budgets and validate that changes do not introduce regressions.
- When prioritising development resources: allocate time to server response times, image optimisation, and JavaScript execution, as these affect LCP, INP, and CLS respectively. For ongoing monitoring, implement daily seo tracking to catch regressions early.
What it is not
- Belief: Core Web Vitals are a single score. Correction: They are three separate metrics, each with its own threshold, and a page can pass or fail individually.
- Belief: Good Core Web Vitals guarantee high rankings. Correction: They are only one part of page experience signals; content relevance and backlinks are far more influential.
- Belief: Lab tests are sufficient to assess Core Web Vitals. Correction: Lab data can indicate potential issues, but only field data from real users provides the true pass/fail status.
- Belief: FID is still the current metric for interactivity. Correction: INP replaced FID in March 2024, and any documentation referring to FID is outdated.
Questions people ask
What are core web vitals?
Core Web Vitals are Google's three user-experience metrics that measure a page's loading speed, interactivity, and visual stability. They are called LCP (Largest Contentful Paint), INP (Interaction to Next Paint), and CLS (Cumulative Layout Shift). These metrics are based on real-world user data and are part of Google's page experience signals.
What is core web vitals?
Core Web Vitals is a set of three specific metrics that Google uses to evaluate the user experience of a web page. They focus on loading performance (LCP), responsiveness to interactions (INP), and visual stability (CLS). The metrics are measured from real users and are used alongside other page experience signals in search ranking.
How to improve core web vitals?
Improving Core Web Vitals requires addressing each metric individually. For LCP, optimise server response times, enable text compression, and use efficient image formats. For INP, reduce JavaScript execution time and break up long tasks. For CLS, set explicit dimensions for images and ads, and avoid inserting content above existing content without user interaction. Use field data from Google Search Console to identify the weakest metric and prioritise fixes.
Does core web vitals affect SEO?
Core Web Vitals are part of Google's page experience signals, which can influence search performance. However, they are not a direct ranking factor on their own; they are considered alongside other signals such as mobile-friendliness, HTTPS, and intrusive interstitials. A page with poor Core Web Vitals may see a negative impact on rankings, especially if it provides a noticeably bad user experience, but excellent metrics do not compensate for weak content or low relevance.
Sources
- Google Search Central — Understand Core Web Vitals and Google Search results Primary source for definitions, thresholds, and Search relevance.
- Google Search Central — Core Web Vitals report Official explanation of how Google measures and reports CWV in Search Console.
- Google Search Central blog / documentation on INP Best source for the FID-to-INP change and current metric guidance.
- PageSpeed Insights Common diagnostic tool for measuring CWV in lab and field contexts.
Written and maintained by Nora Lindholm. Last updated 27 July 2026.
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