What are Core Web Vitals?
Core Web Vitals are a set of three metrics Google uses to measure the experience real people have on a page: how fast the main content loads, how quickly the page responds to input, and how stable the layout is while it loads. They are part of Google's page experience signals and are reported in Search Console, PageSpeed Insights, and Chrome's tools.
The current three are Largest Contentful Paint (LCP), Interaction to Next Paint (INP), and Cumulative Layout Shift (CLS). INP replaced First Input Delay (FID) as a Core Web Vital in March 2024.
How it works
| Metric | Measures | Good | Poor |
|---|---|---|---|
| LCP | Loading | 2.5 s or less | Over 4 s |
| INP | Responsiveness | 200 ms or less | Over 500 ms |
| CLS | Visual stability | 0.1 or less | Over 0.25 |
Values in between count as "needs improvement". A page passes when it meets the good threshold at the 75th percentile of real visits, measured separately for mobile and desktop. The data comes from the Chrome User Experience Report (CrUX), collected from Chrome users who opted in, over a rolling 28-day window.
Pages without enough traffic have no field data of their own; Search Console groups similar URLs and may fall back to origin-level data.
Google has described Core Web Vitals as a ranking signal, but a modest one. A fast page with weak content will not outrank a relevant, slower one. Passing matters most as a tiebreaker and for keeping visitors.
Example
Search Console's Core Web Vitals report might list 140 mobile URLs as "Poor: LCP issue: longer than 4s (mobile)", grouped under one example URL. They share a blog post template whose hero image is a 1.8 MB JPEG loaded lazily. Serving a compressed WebP, removing loading="lazy" from that image, and preloading it would fix the whole group. After the fix, click Validate fix; the report tracks the next 28 days of field data.
In WordPress
Theme and plugin weight decide most of a WordPress site's vitals. Heavy page builders, sliders, font and icon libraries, and ad or chat scripts are the usual causes. Caching and a CDN help LCP; removing unused scripts helps INP; image dimensions and reserved space for ads help CLS. Hydrogen SEO adds no front-end JavaScript. The hydrogenseo.com platform's web vitals checker tests any URL; see bulk audit and SEO tools.
Common mistakes
- Optimizing for Lighthouse lab scores while field data, which Google uses, is fine or unaffected.
- Still tracking FID, which is retired.
- Testing only desktop when mobile field data is usually worse.
Common questions
Are Core Web Vitals a ranking factor?
Yes, as part of page experience, but Google describes them as one of many signals and less important than relevance and content quality.
Why does my page have no Core Web Vitals data?
CrUX only reports URLs and origins with enough real Chrome traffic. Low-traffic pages may show no data or be grouped with similar pages.