Core Web Vitals explained: LCP, INP and CLS in plain English
What LCP, INP and CLS measure, the scores Google counts as good, and the fixes that improve Core Web Vitals on most websites.
Core Web Vitals are Google's way of measuring how a page feels to a real visitor: how fast the main content appears, how quickly the page responds when you tap something, and whether things jump around while it loads. Here's what each metric means, what counts as a good score, and the fixes that usually help most.
The three metrics at a glance
| Metric | What it measures | Good | Needs improvement | Poor |
|---|---|---|---|---|
| LCP Largest Contentful Paint | Loading: when the biggest image or text block appears | ≤ 2.5 s | 2.5–4 s | > 4 s |
| INP Interaction to Next Paint | Responsiveness: how fast the page reacts to taps, clicks and key presses | ≤ 200 ms | 200–500 ms | > 500 ms |
| CLS Cumulative Layout Shift | Visual stability: how much content moves around unexpectedly | ≤ 0.1 | 0.1–0.25 | > 0.25 |
A page passes when it hits the "good" threshold for at least 75% of real visits (the 75th percentile), measured separately for mobile and desktop.
LCP: how fast the main content loads
LCP is usually your hero image, a banner or a large heading. On most slow sites, the problem is one of these:
- Heavy images. Compress them, serve WebP or AVIF, and size them for the screen they're shown on.
- The LCP image is lazy-loaded. Never lazy-load the main above-the-fold image. Add
fetchpriority="high"to it instead. - Slow server response. Cheap shared hosting, no caching and no CDN all push LCP up. This matters even more for visitors far from your server.
- Render-blocking CSS and JavaScript. Defer scripts that aren't needed for the first view.
INP: how quickly the page responds
A poor INP score means the browser is busy running JavaScript when a visitor tries to interact. Menus open late, buttons feel stuck, and forms lag. Common fixes:
- Remove plugins, widgets and tracking scripts you don't use. Each one adds work for the browser.
- Load chat widgets, heatmaps and other third-party scripts after the page is interactive.
- Ask your developer to break long JavaScript tasks into smaller chunks so the browser can respond in between.
- Keep click handlers light. Show immediate feedback, then do the heavy work.
CLS: stopping the page from jumping
You've felt bad CLS when you go to tap a link and an ad pushes it down at the last second. To fix it:
- Always set
widthandheightattributes on images and videos so the browser reserves space. - Reserve fixed space for ads, embeds and cookie banners.
- Don't insert content above what the visitor is already reading.
- Use
font-display: swapwith a fallback font of similar size so text doesn't reflow when web fonts load.
How to measure your scores
- PageSpeed Insights shows real-user data from the Chrome UX Report (when your site has enough traffic) plus a lab test with specific suggestions.
- Search Console's Core Web Vitals report groups similar URLs and shows which groups pass or fail on mobile and desktop.
- Chrome DevTools (the Performance panel) helps developers find exactly which script or element causes a problem.
Real-user data is based on a rolling 28-day window, so after you ship a fix it takes a few weeks for the new scores to fully show.
Do Core Web Vitals affect rankings?
Yes, but they aren't the most important factor. Google uses Core Web Vitals as part of its page experience signals, and it's clear that relevant, helpful content still wins. A fast page with weak content won't outrank a slower page that answers the search much better.
Where Core Web Vitals really pay off is conversions. Faster, more stable pages keep visitors around longer and lose fewer of them before they call, buy or fill in a form.
Want to know where your site stands? Request a free audit and I'll include a Core Web Vitals review with the fixes that will help most.