What Are Core Web Vitals? LCP, INP and CLS, and How Google Uses Them in 2026

What Are Core Web Vitals, in Google’s Words?

Core Web Vitals are the subset of Google’s Web Vitals metrics that applies to every web page. Google’s web.dev guide, written by the Chrome team, defines them as “the subset of Web Vitals that apply to all web pages, should be measured by all site owners, and will be surfaced across all Google tools” (Web Vitals, last updated October 31, 2024). It calls Web Vitals “an initiative by Google to provide unified guidance for quality signals that are essential to delivering a great user experience on the web.”

Google Search Central describes the same set from the search side. Its page says Core Web Vitals “is a set of metrics that measure real-world user experience for loading performance, interactivity, and visual stability of the page.” Google says it “highly recommend[s] site owners achieve good Core Web Vitals for success with Search” (Understanding Core Web Vitals and Google search results, last updated December 10, 2025).

Core Web Vitals at a Glance

Core Web Vitals come from Google, are measured on real Chrome users and feed one part of Google’s page experience assessment. The table collects the key facts, each from a Google page read on October 8, 2026.

The Three Metrics and Their Thresholds

Each Core Web Vital has a “good” and a “poor” threshold, and anything between is “needs improvement”. Google’s threshold research puts LCP’s good limit at 2,500 ms, INP’s at 200 ms and CLS’s at 0.1. All three are judged at the 75th percentile of page views (Defining the Core Web Vitals metrics thresholds, last updated May 7, 2025).

Ranges as published in Search Console’s Core Web Vitals report help and the PageSpeed Insights documentation. Search Central’s summary page words the targets slightly differently (“less than 200 milliseconds”, “less than 0.1”); the reports themselves count the threshold value as good.

Largest Contentful Paint (LCP)

web.dev: “LCP reports the render time of the largest image, text block, or video visible in the viewport, relative to when the user first navigated to the page.” Because it starts at navigation, it includes redirect time and server response time (LCP).

Interaction to Next Paint (INP)

web.dev: INP “assesses a page’s overall responsiveness to user interactions by observing the latency of all click, tap, and keyboard interactions that occur throughout the lifespan of a user’s visit to a page. The final INP value is the longest interaction observed, ignoring outliers.” On pages with many interactions, one highest interaction is ignored for every 50 (INP). Scrolling and hovering are not counted.

Cumulative Layout Shift (CLS)

web.dev: “CLS is a measure of the largest burst of layout shift scores for every unexpected layout shift that occurs during the entire lifecycle of a page.” A burst, or session window, groups shifts less than one second apart, up to five seconds in total (CLS). CLS is a unitless score, not a time.

Where Core Web Vitals Come From

Google’s Chrome team introduced Core Web Vitals in May 2020, and Google Search added them to ranking in 2021. The original set was LCP, First Input Delay (FID) and CLS. INP replaced FID in March 2024. Each date below comes from a Google post.

The metric set can change again. web.dev says “The metrics that make up Core Web Vitals will evolve over time”, that stable metrics “won’t change more than once per year”, and that new candidates spend at least six months as “pending” before replacing anything.

How Core Web Vitals Are Measured

Core Web Vitals are measured in the field, on real visits, and judged at the 75th percentile. web.dev says a page should meet each target “for most of your users”, and that tools “should consider a page passing if it meets the recommended targets at the 75th percentile for all three of the Core Web Vitals metrics”, segmented across mobile and desktop.

• Field data comes from CrUX. Chrome describes the Chrome User Experience Report as “a dataset that reflects how real-world Chrome users experience popular destinations on the web”, used “by Google Search to inform the page experience ranking factor” (CrUX docs). PageSpeed Insights and the BigQuery dataset both “represent trailing 28-day periods”.
• Low-traffic pages may have no data. Pages and origins need “a large enough number of visitors” to appear in CrUX. PageSpeed Insights then falls back to the whole origin, or shows no field data at all.
• Lab tools cannot measure INP. web.dev notes that Lighthouse loads pages “without a user” and so “cannot measure INP”. It suggests Total Blocking Time (TBT) as a lab proxy.
• Missing INP data has its own rule. PageSpeed Insights passes an aggregation on LCP and CLS alone if INP data is insufficient. If LCP or CLS data is missing, the page “cannot be assessed”.

Sites can also collect their own field data with Google’s open-source web-vitals JavaScript library, which web.dev says measures each metric “in a way that accurately matches how they’re reported by all the Google tools”:

import {onCLS, onINP, onLCP} from 'web-vitals';
onCLS(console.log);
onINP(console.log);
onLCP(console.log);

How Google Search Uses Core Web Vitals

Google Search uses Core Web Vitals in ranking, but as one signal among many, with relevance first. Google’s page experience documentation answers the question directly: “Core Web Vitals are used by our ranking systems.” In the same answer, Google says there is “no single signal” for page experience (Understanding page experience in Google Search results, last updated September 22, 2026).

Google adds four limits that are easy to miss:

• No guarantee. “Getting good results in reports like Search Console’s Core Web Vitals report or third-party tools doesn’t guarantee that your pages will rank at the top of Google Search results.”
• Relevance wins. “Google Search always seeks to show the most relevant content, even if the page experience is sub-par.” Page experience can contribute “for many queries” where lots of helpful content exists.
• Diminishing returns. “Trying to get a perfect score just for SEO reasons may not be the best use of your time.”
• Mostly page by page. Ranking systems “generally evaluate content on a page-specific basis”, though Google says it has “some site-wide assessments”.

Other page experience factors Google lists (HTTPS, mobile display, no intrusive interstitials, not too many ads) “don’t directly help your website rank higher”, in Google’s words, though they align with what its systems reward. Google’s guide to AI features and your website lists “Providing a great page experience for users” among the SEO basics for AI Overviews and AI Mode, without saying how much it weighs. For how ranking changes play out over time, see what happens in a Google core update.

What Core Web Vitals Are Not

Core Web Vitals are not a Lighthouse score, not a site-speed grade and not a ranking guarantee. They are three field metrics, judged at the 75th percentile, from real Chrome visits over 28 days. Several common uses of the term are wrong according to Google’s own documentation:

• Not the Lighthouse performance score. PageSpeed Insights says “Any green score (90+) is considered good” for lab data. That score is a simulation on one device, while Core Web Vitals come from field data. A page can score 95 in Lighthouse and still fail on real phones.
• Not every Web Vital. Time to First Byte (TTFB), First Contentful Paint (FCP) and TBT are supporting metrics. web.dev calls them diagnostic, not Core.
• Not a per-URL verdict in Search Console. The report groups similar URLs and gives each group the status of its worst metric.
• Not the same for mobile and desktop. Each device type is assessed separately.

How to Check Your Core Web Vitals

Check Core Web Vitals in Search Console for the whole site and in PageSpeed Insights for one URL. Search Console’s report “shows how your pages perform, based on real world usage data”, grouped by status (Poor, Need improvement, Good), metric and URL group (Core Web Vitals report). To use it, you first need a verified Search Console property.

1. Open Search Console > Core Web Vitals and choose Mobile or Desktop. Only indexed URLs appear, and data is assigned to the actual URL, not the canonical.
2. Read the issue rows. Group LCP, INP and CLS values are the level that “75% of page requests” met in the last 28 days. A group needs enough data for both LCP and CLS to appear at all.
3. Test an example URL in PageSpeed Insights for page-level field data and lab diagnostics. Google notes PageSpeed Insights strips URL parameters and may not match the group figure.
4. After a fix, wait. Field data covers 28 days, so improvements show gradually. Use the report’s validation feature to track fixed issues.

The Core Web Vitals report is a Google Search Console feature; our Search Console vs Bing Webmaster Tools comparison covers what each tool offers. Performance is also worth re-checking after any large change, such as when you move a website to a new domain.

Core Web Vitals vs Related Terms

Common Misconceptions About Core Web Vitals

Frequently Asked Questions

Sources and Methodology

This explainer is built from Google’s own documentation on web.dev, Google Search Central, Chrome for Developers and Search Console Help, read on October 8, 2026. Definitions are quoted verbatim. We did not measure any site’s Core Web Vitals for this article, and we make no claim about how much Core Web Vitals weigh in ranking beyond what Google states. Google does not publish that weighting. Thresholds can change; web.dev says changes to Core Web Vitals are announced with prior notice on an annual cadence.

1. official web.dev, Web Vitals (Philip Walton; published May 4, 2020, last updated October 31, 2024).
2. official web.dev, Defining the Core Web Vitals metrics thresholds (last updated May 7, 2025).
3. official web.dev, Largest Contentful Paint (LCP), Interaction to Next Paint (INP) and Cumulative Layout Shift (CLS).
4. official web.dev Blog, Interaction to Next Paint is officially a Core Web Vital (Rick Viscomi, March 12, 2024).
5. official Google Search Central, Understanding Core Web Vitals and Google search results (last updated December 10, 2025).
6. official Google Search Central, Understanding page experience in Google Search results (last updated September 22, 2026).
7. official Google Search Central Blog, Introducing INP to Core Web Vitals (Martin Splitt, May 10, 2023; updated January 31 and March 12, 2024).
8. official Google Search Central Blog, Evaluating page experience for a better web (May 28, 2020) and More time, tools, and details on the page experience update (April 19, 2021).
9. official Search Console Help, Core Web Vitals report.
10. official Google for Developers, About PageSpeed Insights (last updated October 21, 2024).
11. official Chrome for Developers, Overview of CrUX.
12. official Google Search Central, AI features and your website (last updated December 10, 2025).