Google has made it official: page experience matters for rankings. Core Web Vitals are the specific metrics Google uses to measure user experience, and they directly impact where your site appears in search results.
What Are Core Web Vitals?
Core Web Vitals are a set of specific factors that Google considers important in a webpage's overall user experience. Introduced in 2020 and becoming a ranking factor in 2021, these metrics measure:
- Loading performance — How fast does content appear?
- Interactivity — How quickly does the page respond to user input?
- Visual stability — Does the page layout shift unexpectedly?
Core Web Vitals are measured on real user data from Chrome users (CrUX data), not just lab tests. This means your actual visitors' experiences determine your scores.
The Three Core Metrics
LCP, INP, and CLS explained
| Metric | Measures | Good | Needs Improvement | Poor |
|---|---|---|---|---|
| LCP Largest Contentful Paint | Loading speed | ≤ 2.5s | 2.5s - 4s | > 4s |
| INP Interaction to Next Paint | Responsiveness | ≤ 200ms | 200ms - 500ms | > 500ms |
| CLS Cumulative Layout Shift | Visual stability | ≤ 0.1 | 0.1 - 0.25 | > 0.25 |
LCP: Largest Contentful Paint
LCP measures how long it takes for the largest content element to become visible. This is the metric users "feel" most directly—it's the moment the page looks loaded.
INP: Interaction to Next Paint
INP replaced FID in March 2024. It measures the time from when a user interacts with your page to when the browser responds with a visual update.
CLS: Cumulative Layout Shift
CLS measures unexpected layout shifts during the page lifecycle. Ever tried to click a button only to have an ad load and push it down? That's a layout shift.
The SEO Impact
Google confirmed that Core Web Vitals are a ranking factor, but with important nuances:
Core Web Vitals are a tiebreaker, not a dominant factor. Content relevance still matters most. But when two pages have similar content quality, the faster one wins.
| Study/Source | Finding |
|---|---|
| Searchmetrics 2023 | Pages with good CWV rank 24% higher on average |
| Ahrefs 2024 | 33% of top 10 results have good CWV scores |
| HTTP Archive | Only 39% of sites pass all three CWV thresholds |
The Conversion Impact
Beyond SEO, Core Web Vitals directly impact your bottom line:
| Improvement | Business Impact |
|---|---|
| 0.1s faster LCP | +8.4% retail conversions |
| 0.1s faster LCP | +10.1% travel conversions |
| Good CLS score | +15% user engagement |
| 1s delay | -7% conversions |
How to Measure Core Web Vitals
Field Data (Real Users)
- Google Search Console — Core Web Vitals report
- PageSpeed Insights — Field and lab data
- Chrome UX Report — Raw data from Chrome users
Lab Data (Simulated)
- Lighthouse — Built into Chrome DevTools
- WebPageTest — Detailed waterfall analysis
- GTmetrix — Easy-to-read reports
Optimization Strategies
Improve LCP
- Preload critical resources — Use <link rel="preload"> for hero images
- Optimize images — Use WebP/AVIF, proper sizing, lazy loading
- Reduce server response time — Use a CDN, optimize TTFB
Improve INP
- Break up long tasks — Use requestIdleCallback
- Reduce JavaScript — Code split, tree shake, lazy load
- Optimize event handlers — Debounce, throttle
Improve CLS
- Set dimensions on images/videos — Always include width/height
- Reserve space for ads — Use min-height on ad containers
- Use font-display: swap — Prevent invisible text
Need Help Optimizing Your Core Web Vitals?
Our performance engineers can audit your site and implement optimizations.
Get a Performance Audit →Frequently Asked Questions
Are Core Web Vitals a major ranking factor?
Core Web Vitals are a confirmed ranking factor, but more of a tiebreaker than a dominant signal. Content relevance and backlinks still matter more.
What's the difference between field data and lab data?
Field data comes from real users. Lab data is simulated. Google uses field data for rankings.
How long does it take for improvements to affect rankings?
Google's CrUX data is collected over a 28-day rolling period. After making improvements, it typically takes 28 days for the new data to be reflected.
Do Core Web Vitals affect mobile and desktop rankings differently?
Yes. Google measures CWV separately for mobile and desktop. Mobile scores affect mobile rankings, desktop scores affect desktop rankings.