Your website might look great — but if it loads slowly, jumps around during scroll, or lags when someone taps a button, Google notices. Core Web Vitals are the three metrics Google uses to measure exactly that. Here's how to check them yourself, for free, and what to do once you know your scores.

What Are Core Web Vitals?

Core Web Vitals are a set of three user experience metrics that Google uses as a ranking signal. They measure loading speed, interactivity, and visual stability:

LCP (Largest Contentful Paint) — how long it takes for the main content (a hero image, heading, or block of text) to appear on screen
INP (Interaction to Next Paint) — how quickly the page responds when a user clicks, taps, or presses a key
CLS (Cumulative Layout Shift) — how much the page layout shifts unexpectedly while loading (think: a button that moves just as you're about to tap it)

Note: Google retired FID (First Input Delay) in March 2024 and replaced it with INP, which measures responsiveness across the full page visit rather than just the first interaction.

What's a Good Score?

Metric	Good	Needs Improvement	Poor
LCP	≤ 2.5s	2.5s – 4.0s	> 4.0s
INP	≤ 200ms	200ms – 500ms	> 500ms
CLS	≤ 0.1	0.1 – 0.25	> 0.25

Aim to be in the "Good" range on all three. Passing Core Web Vitals doesn't guarantee top rankings, but failing them is a clear signal that your site is delivering a poor experience — and Google will rank other sites ahead of yours.

How to Check Core Web Vitals: Step by Step

1. Google PageSpeed Insights (easiest, no account needed)

PageSpeed Insights (PSI) is the quickest way to get a read on your site.

Go to pagespeed.web.dev
Paste in your URL and click Analyse
Wait 10–20 seconds for the report to load

The report has two sections:

Field data (top) — real-world measurements from Chrome users who visited your site over the past 28 days. This is what Google actually uses for ranking. If your site is new or low-traffic, this section may show "insufficient data" — that's normal.

Lab data (below) — a simulated test run under controlled conditions. Useful for diagnosing issues even when field data is sparse.

Look at the three CWV metrics. Green = Good. Orange = Needs Improvement. Red = Poor.

Below the scores, PSI lists Opportunities and Diagnostics — specific things you can fix, with estimated loading time savings. These are worth reading carefully.

2. Google Search Console (for your whole site)

If you've verified your site in Search Console, this gives you a site-wide picture:

Open Search Console and go to Experience → Core Web Vitals
You'll see two reports: Mobile and Desktop
Click into either to see which URLs are failing and why

This is more powerful than PSI because it shows you patterns across your entire site, not just a single page at a time.

3. Chrome DevTools Lighthouse (for developers)

Useful for testing pages behind a login, staging environments, or localhost:

Open Chrome and navigate to the page
Press F12 to open DevTools
Click the Lighthouse tab
Select Performance, set the device to Mobile (stricter and more representative), then click Analyse page load

Lighthouse generates the same metrics as PSI with a detailed breakdown of exactly what's causing each issue.

What the Numbers Are Telling You

Once you have your scores, here's what typically causes each problem:

Slow LCP is almost always an unoptimised hero image, a slow server response, or render-blocking JavaScript. The fix: compress and lazy-load images, use a CDN, and defer non-critical scripts.

High INP usually means JavaScript is monopolising the main thread. The fix: break up long tasks, defer analytics and third-party scripts, and audit heavy UI frameworks for unnecessary re-renders.

High CLS is typically caused by images or ads loading without reserved dimensions, or web fonts causing text to reflow. The fix: always set width and height attributes on images, and use font-display: swap for custom fonts.

Why This Matters for SEO

Google confirmed Core Web Vitals as a ranking factor in 2021 and has continued to weight them more heavily since. Beyond rankings, there's a direct business case: a page that passes all three CWV metrics loads faster, feels more responsive, and stays visually stable — all of which reduce bounce rates and improve conversion.

If your analytics show high bounce rates or short session durations, poor Core Web Vitals are often a contributing factor worth investigating first.

Not Sure What to Fix?

Running the tests is the easy part. Knowing which fixes will have the most impact — and in what order — takes more digging. If your scores are in the orange or red and you'd rather have an expert take a look, that's exactly what our free performance reports are for.