This Core Web Vitals explainer starts with the essentials: they are three measurements Google uses to judge how pleasant a page is to use. They measure how quickly the main content appears (LCP), how quickly the page responds when you click (INP) and how stable the layout stays while loading (CLS).
You don't need to be a developer to understand them. In this article we explain each measurement, the thresholds Google uses, how to test them and what you can do if your site scores badly.
What are Core Web Vitals?
Core Web Vitals are part of what Google calls page experience. Google wants to send visitors to pages that are not only relevant, but also work smoothly and without irritation. These three numbers give an objective picture of that.
Worth knowing: Google mainly uses data from real visitors who view your site in Chrome. That's called field data. A test you run yourself is called lab data. Lab data is handy for finding problems, but field data determines how Google sees your site.
LCP: how quickly does the main content appear?
LCP stands for Largest Contentful Paint. It measures how long it takes for the largest visible element at the top of the page to load. Often that's a large photo, a banner or a heading.
- Good: under 2.5 seconds.
- Needs improvement: between 2.5 and 4 seconds.
- Poor: over 4 seconds.
A poor LCP is usually caused by an oversized image at the top, a slow server or lots of scripts that have to load first. Shrink the main image, use a modern format such as WebP and make sure you have fast hosting. You'll find more tips in making your website faster.
INP: how quickly does your page respond?
INP stands for Interaction to Next Paint. It measures how quickly a page visibly responds when someone clicks, taps or types. Think of a menu opening or a button in a form. INP replaced the older FID measurement in 2024.
- Good: under 200 milliseconds.
- Needs improvement: between 200 and 500 milliseconds.
- Poor: over 500 milliseconds.
A poor INP is often caused by heavy JavaScript, the code that handles interaction on a page. Chat widgets, trackers, sliders and heavy page builders are well-known culprits. Fewer scripts and lighter technology help most here.
CLS: does the layout stay stable?
CLS stands for Cumulative Layout Shift. It measures how much parts of the page jump around while loading. You'll know the feeling: you go to tap a button, a banner suddenly slides into view and you click something else.
- Good: under 0.1.
- Needs improvement: between 0.1 and 0.25.
- Poor: over 0.25.
You can often fix CLS by giving images and videos a fixed width and height. That way the browser reserves space in advance. Also watch out for cookie banners, ads and fonts that load late and make the text shift.
How to test your site's Core Web Vitals
There are a few free Google tools that quickly show you where you stand:
- PageSpeed Insights: enter an address and see both field data (if available) and lab data, with points to improve.
- Google Search Console: under the Core Web Vitals section you can see which groups of pages score well or badly.
- Chrome's developer tools: handy if you want to see with a developer what's slowing a page down.
If your site has few visitors, there may not be any field data yet. Then you look at the lab test. That gives a good indication of where the bottlenecks are.
Note: after an improvement, it takes a while before you see it in Search Console. Google collects field data over a period of about 28 days. A lab test does show the effect straight away. So use that to check whether your change works, and then give the field data time.
Always look at mobile and desktop separately too. A page can score fine on a laptop and be well below the threshold on a phone. Because many visitors arrive on mobile, the mobile score is usually the most important. If your site doesn't work well on a small screen, also read our article on a responsive website.
How important are Core Web Vitals for SEO?
Honest answer: they count, but they're not the most important thing. Good, relevant content that answers the searcher's question carries more weight. A super-fast page with weak content won't reach the top.
Still, they're worth the effort. Between pages with similar content, a better experience can make the difference. And apart from Google: visitors stay longer on a site that's fast and stable. You usually notice that in the number of enquiries. Want to know more about how Google works? Read our SEO explainer and the technical SEO checklist.
Quick wins for better Core Web Vitals scores
First check which of the three measurements scores worst. That's where the biggest gains are. Also check whether the problem affects all pages or only one type, such as blog posts or product pages. If so, the cause is often in the template for those pages, and you fix it for all of them in one go. These steps almost always help:
- Shrink and compress the large image at the top of your pages.
- Remove plug-ins, widgets and trackers you don't really need.
- Give images, videos and ad blocks fixed dimensions.
- Only load videos and maps when someone clicks on them.
- Choose fast hosting and switch on caching.
- Check your scores again after every major change.
Help with Core Web Vitals and visibility
At Violexa we pay attention to these measurements from the very first line of code. When we build a new site, basic SEO is included in the price as standard. A custom website starts from €1,799 excl. VAT (€2,177 incl. VAT) per project.
Want to work on your visibility in a structured way as well, with SEO, Google Ads or social media? Then our online marketing service is a good fit. It starts from €599 excl. VAT (€725 incl. VAT) per month, with no minimum term and cancellable monthly with one month's notice.
Curious how your site scores and what you can do about it? Book a free quickscan. In 30 minutes, online or on site, we look at your site together. Afterwards you get brief written advice with a price indication, with no obligation.
Frequently asked questions
What is a good Core Web Vitals score?
Google calls a page good if LCP is under 2.5 seconds, INP under 200 milliseconds and CLS under 0.1. Google looks at the experience of real visitors. Most visits need to fall within those limits.
What is the difference between FID and INP?
FID only measured how quickly a page started to respond to the first click. INP looks at all interactions during a visit and measures when the result becomes visible. INP replaced FID in 2024.
Why can't I see Core Web Vitals in Search Console?
Google doesn't have enough data from real visitors yet. This often happens with new sites or sites with little traffic. In that case, use PageSpeed Insights for a lab test.
Do Core Web Vitals affect my ranking in Google?
Yes, but only to a limited extent. Relevant, good content carries more weight. The measurements can make the difference between similar pages, though, and a fast site holds on to visitors better.
