Web Design
What Are Core Web Vitals and Why Should Your Business Care?
You’ve done it yourself. You tap a link on your phone, wait a second or two, and then just… close the tab. No conscious decision. Just a reflex.
Google has tracked this behaviour at scale. Their own research found that more than half of all mobile visits are abandoned if a page takes longer than three seconds to load. That pattern is exactly what Core Web Vitals was designed to measure: whether your website actually works for real visitors, on real devices, in real conditions.
But this isn’t just a search engine story. A site that passes Core Web Vitals is faster, more stable, and easier to use. Visitors feel that difference, and it shows up in whether they stay, enquire, or buy.
What are Core Web Vitals?
Core Web Vitals are three specific measurements Google uses to assess the quality of experience on a website. They don’t measure how the site looks or whether the copy is good. They measure how it feels to use: how quickly it loads, how fast it responds to clicks, and whether the layout jumps around while you’re reading.
What sets Core Web Vitals apart from older speed scores is that they’re based on data from real Chrome users, not simulated lab tests. Google collects anonymised performance data through the Chrome User Experience Report (CrUX) and evaluates your site against the 75th percentile of that data. That means 75% of your visitors’ actual experiences are what counts — not just the best or worst cases.
The framework launched in 2021 and was updated in March 2024, when one of the three metrics was replaced with a more accurate measure of interactivity.
The three metrics — what do they actually measure?
LCP — how quickly does the main content load?
LCP, or Largest Contentful Paint, measures how long it takes for the largest visible element on the page to finish rendering. That’s usually your hero image, main headline, or a product photo — whatever the visitor is actually waiting to see.
Google’s threshold for a good LCP score is 2.5 seconds. Over 4 seconds is classified as poor.
It’s the metric most sites fail. HTTP Archive, which continuously analyses millions of websites, shows that roughly half of all mobile pages pass the LCP threshold. One of the most common causes is a slow server response from the very start — when the server takes a little too long to send the first byte, the entire time budget is eaten up before the image has even started downloading. (There’s a reason first impressions happen so fast. If you want to understand what those first milliseconds do to a visitor’s judgement, the article Say It All in 50 Milliseconds covers it well.)
INP — does the page respond when you click?
INP, or Interaction to Next Paint, measures how quickly the page reacts visually when you click, tap, or type something. A menu item, a form field, a button — anything that’s supposed to do something when you interact with it.
The threshold for a good INP score is 200 milliseconds. Over 500 milliseconds is poor.
This metric replaced the older FID (First Input Delay) in March 2024. FID only measured your very first interaction with a page. INP measures every interaction across the entire visit and reports a value representative of the worst experiences. It’s a tougher and more honest assessment. When INP became the official metric, the global pass rate dropped by around five percentage points overnight — which tells you how many sites FID had been quietly flattering.
At its core, INP is a JavaScript problem. Heavy scripts, third-party widgets, and a page trying to do too much at once all make clicks feel sluggish or delayed.
CLS — does the layout jump around?
CLS, or Cumulative Layout Shift, measures how much the page content moves unexpectedly while you’re reading it. Images that pop in and push the text down. A cookie banner that appears and shifts everything. An ad that loads last and knocks the button you were about to tap off the screen.
The threshold for a good CLS score is 0.10. Over 0.25 is poor.
It’s easy to miss in testing because it’s most noticeable on slower connections and older devices — which is exactly where a lot of your visitors are. The most common cause is images shipped without defined width and height attributes. When the browser doesn’t know how big an image is, it doesn’t reserve space for it. When the image loads, everything around it shifts.
Why does Google care about this?
Core Web Vitals are a confirmed ranking signal. Google has said so directly. Their Search Central documentation, last updated in December 2025, states plainly: “Core Web Vitals are used by our ranking systems.”
That doesn’t mean they’re the deciding factor between page one and page three. Google’s own John Mueller has consistently pointed out that relevance, authority, and content quality carry more weight. But Core Web Vitals are part of the picture, and they’re measured against real visitor data from your actual site.
The stronger argument for taking them seriously isn’t ranking — it’s business impact. In 2020, Deloitte conducted a study commissioned by Google across more than 30 million sessions on 37 brand websites across Europe and the US. A 0.1-second improvement in load time increased retail conversion rates by 8.4% and average order value by 9.2%. For lead generation, form completion rates improved by 21.6%.
It’s not the search engine that loses when your site is slow. It’s you.
What do Core Web Vitals have to do with AI search?
A lot of businesses are thinking about AI search right now — whether they show up in ChatGPT answers, or get cited in Google’s AI Overviews. Core Web Vitals play a role here, but not in the way most people expect.
Google has confirmed that AI Overviews uses the same ranking systems as regular search. Their official documentation for AI features states: “We’ve integrated our core web ranking systems into this experience.” So a site that ranks well in standard search has better odds of being cited in AI results too. Core Web Vitals feed into that indirectly.
A January 2026 analysis published in Search Engine Land examined 107,352 pages cited prominently in Google AI Overviews and AI Mode. The conclusion is worth keeping: good performance doesn’t create an advantage, but severe failure can filter you out. Core Web Vitals act as a floor for AI visibility. Get the basics right and you’re protected. A perfect score gives no measurable edge over everything else you could spend that time on.
WordPress and Core Web Vitals — a known challenge
A lot of business websites are built on WordPress, and WordPress is the major CMS platform that struggles most with Core Web Vitals on mobile. HTTP Archive data shows around 40% of WordPress sites pass all three metrics on mobile, compared to 70–73% for simpler platforms.
That’s rarely WordPress’s fault in itself. It’s how the site was built.
Heavy page builders like Elementor and Divi load large amounts of code the page may not even need. Images that were never converted to modern formats burn through the LCP budget. Plugins that inject scripts on every page slow down interactivity. And hosting with a high server response time means the whole chain starts at a disadvantage.
None of these are unsolvable problems. They’re well-understood problems with well-understood fixes: better hosting, smart caching, image optimisation, and themes that don’t carry unnecessary code. But you need to know what you’re looking for. That’s exactly what we handle at Monprez when building and maintaining websites for businesses. If you’re curious what actually happens to a site after it goes live, the article on WordPress maintenance and what it means in practice covers that in detail.
How do you know how your site is performing?
The easiest starting point is Google PageSpeed Insights (pagespeed.web.dev). Paste in your URL and the tool gives you both a lab score and, if enough data exists, real field data from actual visitors. It’s free and needs no login.
If you want to see the picture across your whole site rather than individual pages, the Core Web Vitals report in Google Search Console is more useful. It groups pages with similar performance together and shows where problems are systematic — for example, if all your blog posts or all your service pages are failing the same metric.
Neither tool requires a technical background to understand. Green is good, yellow needs work, red is a problem. Start there.
Common questions about Core Web Vitals
What counts as a good Core Web Vitals score?
Google classifies sites into three levels: good, needs improvement, and poor. The goal is to reach the green zone on all three metrics: LCP under 2.5 seconds, INP under 200 milliseconds, and CLS under 0.10. That assessment is made at the 75th percentile of your visitor data, separately for mobile and desktop.
Do Core Web Vitals affect my Google ranking?
Yes, but in a limited way. Google confirms they’re used in their ranking systems, but they don’t carry the same weight as relevant content, authority, and trustworthiness. You can rank well with great content despite weak Core Web Vitals scores, and you can have perfect scores without ranking at all if your content doesn’t match what people are searching for.
Do I need to worry about Core Web Vitals if I have a small website?
Yes, but keep things in proportion. For a small site with limited traffic, Core Web Vitals rarely determine outcomes on their own. The priority is making sure you don’t have severe problems that are actively hurting the experience. Google also notes that sites without enough CrUX data — typically smaller sites with low traffic — may not have the metric applied to their ranking at all.
Do Core Web Vitals affect AI search visibility in tools like ChatGPT and Perplexity?
Indirectly, yes. Google AI Overviews uses the same ranking systems as regular search, so a well-performing site has better standing going in. For other AI tools like ChatGPT and Perplexity, there’s no confirmed direct connection to Core Web Vitals scores. What consistently matters most for AI citation is content quality, authority, and making sure your site is technically accessible to the crawlers that gather information.
Not sure where your site stands? We’re happy to take a look. Get in touch with Monprez and we’ll go through what could be improved for your specific site.