Glossary

What is Core Web Vitals?

By SearchChamp teamUpdated

Core Web Vitals are Google's set of real-world performance metrics that measure user experience quality and serve as confirmed ranking signals. As of 2024, the three metrics are: Largest Contentful Paint (LCP) — how long the largest visible element takes to render, target under 2.5 seconds; Interaction to Next Paint (INP) — how quickly the page responds to user interactions, target under 200 milliseconds (INP replaced First Input Delay in March 2024); and Cumulative Layout Shift (CLS) — how much the page layout shifts unexpectedly during load, target below 0.1. All three are measured from real user data collected in the Chrome User Experience Report (CrUX), not synthetic lab tests. Google confirmed Core Web Vitals as a Page Experience ranking signal in May 2021.

Core Web Vitals in context

Google introduced the Core Web Vitals initiative in 2020 as a way to standardize and quantify user experience. The original three metrics (LCP, FID, CLS) became ranking signals in May 2021 via the Page Experience update. In March 2024, Interaction to Next Paint (INP) replaced First Input Delay (FID) as the responsiveness metric — FID measured time to first interaction; INP measures the worst interaction latency across all user inputs during the page lifecycle, a significantly more comprehensive signal. As of 2026, passing all three Core Web Vitals at the 75th-percentile threshold qualifies a page as 'Good' in Google's assessment. Pages with 'Poor' Core Web Vitals face a measurable ranking penalty, estimated at 1-3 ranking positions on competitive queries.

Example

A B2B SaaS landing page has the following CrUX measurements: LCP 4.2s (Poor, target <2.5s), INP 180ms (Needs Improvement, target <200ms), CLS 0.18 (Poor, target <0.1). The LCP is caused by a 900KB hero image loaded without lazy-loading and no preload hint. The CLS is caused by an unspecified-size ad slot that shifts content when it loads. After fixes — WebP hero image (120KB) with preload hint, ad slot with explicit height dimensions — the page hits LCP 1.4s, INP 95ms, CLS 0.02. All three now in the 'Good' range. Google Search Console reports the page moving from 'Poor' to 'Good' in the Core Web Vitals report within 28 days (CrUX data lags by 28 days).

Related terms

Technical SEO

Making a site crawlable, renderable, indexable, and fast.

Mobile-First Indexing

Google's practice of using the mobile version as the primary index source.

E-E-A-T

Google's quality framework: Experience, Expertise, Authoritativeness, Trust.

FAQ

Common questions about Core Web Vitals.

Passing all three metrics at the 75th-percentile threshold: LCP under 2.5 seconds, INP under 200 milliseconds, CLS below 0.1. Google labels a page "Good" only when all three pass — a page that's excellent on two metrics but "Poor" on the third is still classified "Poor" overall, since Core Web Vitals assessment doesn't average across metrics.
Yes — they remain a confirmed Google ranking signal since the May 2021 Page Experience update, and the metrics have only gotten more scrutinized (INP replaced the more forgiving FID in March 2024). They're not the dominant ranking factor content quality and backlinks are, but on competitive queries where content quality is roughly comparable, Core Web Vitals can be the deciding factor — Google has estimated a 1-3 position penalty for "Poor" pages on competitive terms.
Interaction to Next Paint (INP) replaced FID in March 2024. FID measured the delay before a browser could process the first user interaction. INP measures the latency from any user interaction (click, tap, keyboard input) to the next visual response, assessed across all interactions during the page's lifecycle. INP is harder to pass than FID — it exposes slow JavaScript execution that FID often missed.
From real users. Google sources Core Web Vitals data from the Chrome User Experience Report (CrUX), which aggregates field data from Chrome users who have opted in to Usage Statistics reporting. PageSpeed Insights and Lighthouse provide lab simulations (useful for debugging), but the actual ranking signal uses the 28-day CrUX rolling average at the 75th percentile for each URL. Pages without enough CrUX data fall back to the origin-level (site-wide) score.
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