What Are Core Web Vitals (CWV)?

Core Web Vitals are part of Google's page experience signals. Google measures the current set — LCP, INP, and CLS — using data from real Chrome users, judged at the 75th percentile of page loads and split across mobile and desktop.

For SEO, Google no longer calls Core Web Vitals a standalone ranking factor. Its Search Central documentation says it highly recommends achieving good Core Web Vitals for success with Search, because good scores align with what its core ranking systems seek to reward — while cautioning that page experience doesn't override strong, relevant content. The practical rule: treat Core Web Vitals as a tie-breaker between comparably relevant pages and as a user experience and conversion lever in its own right, not as a substitute for better content.

The three metrics and their "good" thresholds

Each Core Web Vital tracks a distinct facet of user experience, and each has a published "good" threshold:

• Largest Contentful Paint (LCP) measures loading performance — good is within 2.5 seconds of the page starting to load.
• Interaction to Next Paint (INP) measures responsiveness — good is 200 milliseconds or less.
• Cumulative Layout Shift (CLS) measures visual stability — good is a score of 0.1 or less.

A page passes the Core Web Vitals assessment when all three metrics rate "good" at the 75th percentile of page loads, with mobile and desktop assessed separately. Each metric falls into one of three bands — Good, Needs Improvement, or Poor — and each has to clear the bar on its own: a fast-loading page can still fail on layout shift.

INP replaced FID in March 2024

First Input Delay (FID) is no longer a Core Web Vital. Interaction to Next Paint (INP) officially replaced it as the responsiveness metric on March 12, 2024; Google removed FID from Search Console the same day and deprecated it across its remaining tools by September 2024. The change raised the bar: FID measured only the delay before a page's first interaction, while INP measures responsiveness across all interactions in a visit — so pages that comfortably passed FID can fail INP. If a report or audit still cites FID, it predates March 2024 and needs updating.

Measuring Core Web Vitals

Two free tools cover most needs: Google PageSpeed Insights for checking a single URL, and Google Search Console's Core Web Vitals report for spotting sitewide patterns across grouped URLs. Both report field data from the Chrome UX Report (CrUX) — measurements collected from real Chrome users — and both apply the same pass rule: all three metrics "good" at the 75th percentile, mobile and desktop reported separately.

PageSpeed Insights also shows a lab section powered by Lighthouse. Treat it as a diagnostic, not a verdict: lab tests run without a real user interacting, so they can't measure INP, and a page can look fast in the lab while failing its real-user assessment.

Improving Core Web Vitals

Each metric has characteristic failure modes with known fixes:

• Slow LCP: compress and preload the hero image, serve pages through caching or a CDN, and cut server response time.
• High CLS: set explicit width and height on images, embeds, and ad slots, and never inject content above what's already rendered.
• Poor INP: break up long JavaScript tasks and defer — or drop — third-party scripts.

Start with whichever metric your report flags, then re-test after fresh field data comes in. For a step-by-step walkthrough, see DreamHost's 10 tips for improving Core Web Vitals.