What are Core Web Vitals?
By Ash, Founder, HosteazePublished 2 min read
The short answer
Core Web Vitals are three measurements Google uses to judge how a page feels to real visitors. Largest Contentful Paint (LCP) covers loading speed, Interaction to Next Paint (INP) covers responsiveness and Cumulative Layout Shift (CLS) covers visual stability. A good page scores LCP 2.5 seconds or less, INP 200 milliseconds or less and CLS 0.1 or less.
Core Web Vitals are Google's way of putting numbers on things visitors notice without thinking about them. Did the main picture appear quickly? Did the menu open when I tapped it? Did the button jump just as I went to press it? Each of those has a metric, a target and a place to check your score.
What do the three metrics measure?
| Metric | What it measures | Good | Needs improvement | Poor |
|---|---|---|---|---|
| Largest Contentful Paint (LCP) | How long the biggest image or block of text in view takes to appear | 2.5 s or less | 2.5 to 4 s | Over 4 s |
| Interaction to Next Paint (INP) | How quickly the page reacts after a click, tap or key press | 200 ms or less | 200 to 500 ms | Over 500 ms |
| Cumulative Layout Shift (CLS) | How much the page jumps around while it loads | 0.1 or less | 0.1 to 0.25 | Over 0.25 |
On most small business home pages, the LCP element is the hero photo at the top. INP tends to suffer on pages heavy with sliders, chat widgets and tracking scripts. CLS is the one you've felt yourself: a cookie banner or advert loads late and pushes the text down while you're reading.
How does Google decide whether a page passes?
Google looks at real visits, not a single test. It takes the 75th percentile of page loads over the previous 28 days, split into mobile and desktop. In plain terms, three out of four visits need to hit the "good" mark for each metric.
A page passes the Core Web Vitals assessment when all three metrics are good. If there isn't enough INP data, LCP and CLS decide it on their own.
This data comes from the Chrome User Experience Report (CrUX), which collects anonymous timings from Chrome users who've opted in. A quiet site may not have enough visits to appear in it, which is why some small sites see "no data" in Search Console.
Do Core Web Vitals affect my Google ranking?
They do, but less than people fear. Google says its ranking systems use Core Web Vitals. It also says the most relevant content can still rank with a weaker page experience, and that chasing a perfect score just for SEO "may not be the best use of your time".
Our view: get all three into the green, then spend your energy on content. A slow site loses enquiries long before it loses rankings, because people give up and press back.
How do I check my Core Web Vitals?
- Go to PageSpeed Insights at pagespeed.web.dev and enter your page's address.
- Read the top section first. That's the real-user (field) data from CrUX.
- Scroll down to the Lighthouse results. That's a one-off lab test, useful for finding causes but not what Google uses.
- In Google Search Console, open Core Web Vitals to see which groups of pages need work.
Our guide on how to test website speed explains why the two sets of numbers often disagree. If LCP is your weak spot, start with how to improve Largest Contentful Paint. On WordPress, the usual culprits are covered in why is my WordPress site slow.
More plain-English guides are in Email and domains.
Frequently asked questions
Are Core Web Vitals a Google ranking factor?
Yes. Google's page experience documentation says Core Web Vitals are used by its ranking systems. Google also says relevant content still wins, so a perfect score won't lift a weak page above a better answer.
What happened to First Input Delay (FID)?
Interaction to Next Paint replaced First Input Delay as a Core Web Vital on 12 March 2024. INP looks at every click, tap and key press during a visit, not just the first one, so it gives a fuller picture of how responsive a page is.
Why does my site have no Core Web Vitals data?
The real-user figures come from the Chrome User Experience Report, which only covers public pages with enough visits from opted-in Chrome users. Smaller sites often show no data at page level, and sometimes none for the whole site. Lab tests such as Lighthouse still work.