Core Web Vitals are three official Google metrics that measure the real user experience of a web page: loading speed (LCP), responsiveness to interactions (INP) and visual stability (CLS). Meeting the thresholds recommended by Google is not just a SEO technicality: it has a direct impact on how many visitors stay on the site and complete a purchase or a contact request.
In brief
- LCP (Largest Contentful Paint): measures how long it takes for the main content of the page to load. Recommended threshold: under 2.5 seconds.
- INP (Interaction to Next Paint): measures how responsive the site is to user interactions. Recommended threshold: under 200 milliseconds.
- CLS (Cumulative Layout Shift): measures how much the page “shifts” visually while loading. Recommended threshold: under 0.1.
- They are public metrics defined by Google, used both as a ranking signal and as a direct indicator of user experience.
- A slow or unstable site loses visitors and conversions before the SEO factor even comes into play.
What Core Web Vitals really are
Core Web Vitals are a set of metrics introduced by Google to objectively measure the quality of the user experience on a web page, beyond subjective opinions about “how fast” a site feels. There are three of them: LCP (loading speed of the main content), INP (site responsiveness when the user clicks, types or interacts) and CLS (visual stability of the page while it loads). Google uses them both as one of the signals that make up the ranking algorithm and — what is often more relevant for a business — as a direct indicator of the quality of the experience the site offers to its visitors.
The official thresholds: what “good”, “needs improvement” and “poor” mean
Google classifies each metric into three bands, measured on the 75th percentile of real visits (not on a single isolated test). Knowing these thresholds is the first step to understanding whether your site really has a performance problem or whether subjective perceptions do not match the data.
| Metric | What it measures | Good | Needs improvement | Poor |
|---|---|---|---|---|
| LCP | Loading speed of the main content | ≤ 2.5s | 2.5s – 4s | > 4s |
| INP | Responsiveness to user interactions | ≤ 200ms | 200ms – 500ms | > 500ms |
| CLS | Visual stability while loading | ≤ 0.1 | 0.1 – 0.25 | > 0.25 |
How Core Web Vitals are measured
Core Web Vitals are measured in two complementary ways: “field data”, collected by Google directly from real visits by Chrome users through the Chrome User Experience Report, and “lab data”, generated by tools such as PageSpeed Insights or Lighthouse that simulate the page loading under controlled conditions. Field data are the ones that really matter for ranking, because they reflect the real experience of users on different connections and devices; lab data are useful during development to identify and fix problems before they affect real users. Free tools such as Google Search Console, in the “Core Web Vitals” section, show the real state of the site broken down by groups of pages.
Why they really affect a business website’s sales
The link between Core Web Vitals and sales is not just a matter of SEO positioning, but of measurable human behaviour. A visitor who waits more than a few seconds for a page to load tends to abandon it before even seeing the offer; a button that does not respond immediately to a click generates frustration and distrust in the site; a layout that “jumps” while loading (for example, a button that moves just as the user is about to click it) leads to accidental clicks and a perception of poor site quality, even when the content itself is valid. On a business site, this concretely translates into fewer completed contact requests, fewer products added to the cart and a higher abandonment rate already in the early stages of the browsing journey, before the user even evaluates the content or the offer.
How to improve the Core Web Vitals of a business website
Improving these metrics requires targeted interventions on several technical levels, often in combination with each other:
- Optimise images: compression, modern formats (WebP/AVIF) and correct sizing for each device drastically reduce loading times.
- Reduce and optimise JavaScript: heavy or unnecessary scripts slow down both loading and responsiveness to interactions.
- Choose adequate hosting: a slow server, or one shared with too many other sites, penalises every other optimisation made upstream.
- Reserve space for dynamic elements (images, banners, advertising) before they load, to avoid sudden layout shifts.
- Enable caching and a CDN: they reduce server response time, especially for visitors who are geographically distant.
Our performance improvement service works exactly on these fronts: it analyses the site’s real data, identifies the specific bottlenecks and intervenes with priority on the optimisations that deliver the greatest measurable benefit, instead of applying generic fixes that often do not solve the underlying problem.
The most common mistakes that worsen Core Web Vitals
In our experience on projects of this kind, some mistakes recur more often than others and, on their own, explain most of the poor scores detected on business websites:
- Images uploaded without compression, often in the original camera format, much heavier than necessary for the web.
- Too many plugins or third-party scripts (chat, tracking pixels, social widgets) all loaded together when the page opens.
- Custom fonts loaded in a non-optimised way, which delay the display of the main text.
- Undersized shared hosting compared with the site’s real traffic, which slows down every request regardless of frontend optimisations.
- Banners, popups or advertising elements that load late and shift content that is already visible, generating visual instability.
The good news is that none of these problems necessarily requires rebuilding the site from scratch: in most cases these are targeted interventions, identifiable through a precise technical analysis of the most visited pages. Starting from the pages with the most traffic, rather than from the site as a whole, often makes it possible to achieve a noticeable improvement within the first few weeks of intervention.
Frequently asked questions
Do Core Web Vitals really affect Google rankings?
Yes, they are one of the signals Google uses in the ranking algorithm, although not the most decisive one compared with content quality. However, their greatest impact remains on the direct user experience: a slow site loses conversions even when it still manages to rank well.
How do I check my site’s Core Web Vitals?
The most reliable way is to consult the “Core Web Vitals” section of Google Search Console, which shows real data collected from the site’s actual users. Alternatively, PageSpeed Insights provides both field data and a lab simulation, useful for quick tests on individual pages.
Can a WordPress site have good Core Web Vitals?
Yes, but it requires attention: heavy themes, too many unoptimised plugins and inadequate hosting are the most common causes of poor Core Web Vitals on WordPress. With a targeted configuration, a WordPress site can achieve excellent scores on all three metrics.
How long does it take to improve the Core Web Vitals of an existing site?
On average, for interventions of this kind, the first measurable improvements are already visible after the first targeted optimisations (images, caching, scripts), while a stable consolidation across all metrics generally takes several weeks, including the time needed for Google to collect new real field data.
