What Is Core Web Vitals and How Do You Check Yours for Free?

The Three Numbers, Plainly Explained

Core Web Vitals are Google's way of scoring how a page feels to a real person. Not how fast your server is in theory, not how fast it loads on your laptop — how it feels to a visitor on a normal phone on a normal connection. There are three metrics, and each one measures a different kind of annoyance.

LCP — Largest Contentful Paint (loading)

LCP measures how long it takes for the biggest visible piece of content to appear — usually the hero image or the main headline block. Good is under 2.5 seconds. Between 2.5 and 4 seconds needs improvement. Over 4 seconds is poor. If your LCP is bad, visitors stare at a blank or half-loaded page, and a lot of them leave before they read a word.

INP — Interaction to Next Paint (responsiveness)

INP measures the delay between a visitor doing something — clicking a button, tapping a menu, typing in a field — and the page visibly responding. Good is under 200 milliseconds. INP replaced the older FID metric in March 2024, and it is stricter: it measures the worst interactions across the whole visit, not just the first one. A page can load fast and still feel broken if every click takes half a second to register.

CLS — Cumulative Layout Shift (stability)

CLS measures how much the page jumps around while it loads. Good is under 0.1. You know the feeling: you are about to tap a link and an ad loads above it, shoving the whole page down, and you tap the wrong thing. That is CLS, and it is the metric most sites fail for the silliest reasons — images with no dimensions, late-loading ads, fonts that swap after the page renders.

Why Google Cares (and Why You Should)

Google made these a ranking factor because they track what users actually hate. A slow, jumpy page costs you twice: some visitors leave before they convert, and Google ranks you a little lower for it. The ranking effect is small compared to content quality — a great article on a slow page still beats a thin article on a fast one. But when two pages are equal on content, the faster one wins. And on mobile, where most traffic now lives, the gap between a good and a bad score is the gap between a reader and a bounce.

How to Check Yours for Free

1. PageSpeed Insights — the fastest check

Go to pagespeed.web.dev, paste any URL, and you get a full report in under a minute: LCP, INP and CLS for mobile and desktop, plus a prioritized list of what to fix. It uses real Chrome user data when available, so the numbers reflect actual visitors, not just a lab test. Start here.

2. Google Search Console — your whole site at once

Search Console has a dedicated Core Web Vitals report that groups your URLs into Good, Needs Improvement and Poor, for mobile and desktop separately. This is the view that matters for rankings, because it is built from the same real-user data Google uses. If you run a site and have not connected Search Console yet, do that first — it is free and it is the only place you see every page at once.

3. Lighthouse — built into Chrome

Open Chrome DevTools, go to the Lighthouse tab, and run a performance audit on any page. It gives you the same metrics plus a detailed breakdown of what is slowing things down — which scripts, which images, which render-blocking resources. Useful when PageSpeed tells you something is wrong and you want to know exactly what.

4. Web Vitals extension — check as you browse

Google's Web Vitals extension puts a small overlay on any page you visit, showing live LCP, INP and CLS as you scroll and click. It is the quickest way to compare your site against a competitor's, or to catch a layout shift the lab tools missed.

Reading Your Results Without Panicking

Do not chase a perfect 100. A page with a big hero image and a video embed will rarely score like a plain text page, and that is fine. What matters is the traffic-light rating: Good, Needs Improvement, or Poor. Fix Poor first, then Needs Improvement, and accept that some pages will never be perfect. Also check mobile separately — most sites pass on desktop and fail on mobile, and mobile is where your visitors are.

Quick Fixes That Actually Move the Numbers

Most bad scores come from a short list of causes. Compress images and serve them in modern formats — this alone often fixes LCP. Set width and height on every image and embed, so the browser reserves the space and nothing jumps — that fixes CLS. Defer or remove scripts you do not need, especially third-party widgets and trackers — that fixes INP. Use a caching plugin and a CDN if you run WordPress. And if your host is slow, no plugin will save you: the server response time is the floor everything else stands on.

Where Hosting Fits In

Your host controls the single biggest input to LCP: how fast the server answers. Shared hosting on an overloaded server can add a full second before anything else even starts. That is why a cheap host that looks fine on a test page can still fail Core Web Vitals on a real site. If your scores are bad and your images are already optimized, the host is the next thing to check. Our Hostinger review looks at whether budget hosting can actually keep up, and our shared hosting vs VPS guide explains when it is time to move up. If you are starting from scratch, our guide to starting a website in 2026 covers hosting choice from the beginning.

Check your homepage in PageSpeed Insights today. If it is green, you are done — spend the time on content instead. If it is red, start with images and scripts. The fixes are usually boring, and that is good news: boring fixes are cheap, and they work.