The Core Web Vitals are a set of measurable metrics defined by Google that describe the actual quality of a website experience from the user's perspective. Instead of talking in general terms about "speed", Google breaks down the user experience into three specific, measurable dimensions: How quickly is the main content visible? How quickly does the page respond to input? And how stable does the layout remain while the page loads? The Core Web Vitals are part of the overarching "Page Experience" signals and have been included in the Google ranking since 2021.
The three core metricsAs of 2024/2025, the Core Web Vitals consist of three metrics:
- Largest Contentful Paint (LCP) - measures Load Perception: When is the largest visible element in the viewport (usually an image or a large text block) finished loading? Guide value: under 2.5 seconds is considered good, over 4.0 seconds is considered bad.
- Interaction to Next Paint (INP) - measures the responsiveness: How long does it take from a user interaction (click, tap) to the visible response of the page? INP replaced the previous metric First Input Delay (FID) in March 2024 because it maps the entire interaction behaviour over the page visit, not just the first input. Guide value: under 200 milliseconds is considered good. Cumulative Layout Shift (CLS) - measures the visual stability: How much does the layout shift during loading, for example because an image is reloaded without reserved space or a banner slips in? Guide value: under 0.1 is considered good, over 0.25 is considered bad.
Laboratory versus field data
A key point that is often overlooked: Google evaluates Core Web Vitals for ranking based on field data - real measurements from real users, collected in the Chrome User Experience Report (CrUX). Tools such as Lighthouse or PageSpeed Insights, on the other hand, often provide lab data from a simulated environment. Both can deviate. What counts for the SEO evaluation is what the Search Console reports from the field data, not the unique Lighthouse score on the developer laptop.
Why the Core Web Vitals count for e-commerce
Core Web Vitals are doubly relevant for online retailers for two reasons. Firstly, as a ranking factor: although they are not the strongest lever - relevance and content weigh more heavily - they can tip the scales if their relevance is comparable. Secondly, and often more importantly, as a conversion factor: a slow, unstable site frustrates visitors and costs sales, regardless of ranking. Studies by Google and large retailers repeatedly show that even small improvements in loading time have measurable effects on bounce rates and order completion.
Shops in particular are susceptible: large product images drive up the LCP, lots of JavaScript (tracking, personalisation, chat widgets) worsens the INP, and reloaded advertising banners or cookie layers without reserved space ruin the CLS. If you work cleanly here, you improve SEO and conversion at the same time.Typical causes of poor values - and countermeasures
| Metrics | Common cause | Countermeasure |
|---|---|---|
| LCP | Large, unoptimised images; slow server | Modern image formats (WebP/AVIF), lazy loading with priority for LCP image, CDN, caching |
| INP | Too much and blocking JavaScript | Splitting scripts, delaying, removing unused code, splitting tasks into small chunks |
| CLS | Images/displays without fixed dimensions, late-loading fonts | Set width and height to media, reserve space for banners, preload fonts |
A concrete example
A typical Shopware scenario: The start page of a shop shows a large hero banner. If this image is delivered as an uncompressed JPEG with several megabytes, the LCP takes just over four seconds - "bad". If the same image is delivered as a correctly dimensioned WebP via a CDN and given high loading priority, the LCP often drops below 2.5 seconds. If a cookie banner is added, which slides in from above after 800 milliseconds and pushes the content downwards, this has an impact on the CLS - if the space is reserved in advance instead, the layout remains stable. Such interventions are often manageable in terms of effort, but their effect is easy to measure.
How to measure the values
There are several complementary tools for measurement: the Google Search Console (Core Web Vitals report, based on real field data), PageSpeed Insights (combines field and lab data), Lighthouse (lab data, integrated into Chrome) and the Chrome DevTools for detailed analysis. For ongoing monitoring, we recommend taking a look at the Search Console, as it shows which URL groups are missing Google's thresholds.
Frequent misunderstandingsFirstly: A perfect Lighthouse score of 100 does not automatically mean good Core Web Vitals - the field data of real users is decisive. Secondly, Core Web Vitals are not a "mega ranking factor" that saves bad content; they act as a fine-tuning tool. Thirdly, the myth that FID is still relevant persists - INP replaced FID in March 2024. Fourthly, the thresholds are not binary "pass/fail" goals, but a guide; Google evaluates the 75th percentile of user experience.
Outlook
The Core Web Vitals are not a static construct. Google adjusts the metrics when new insights about the user experience are available - the change from FID to INP is the best example. For retailers, this means that performance is not a one-off project, but an ongoing task that needs to be considered with every relaunch, every new tracking script and every theme update. The official, continuously updated reference is web.dev/vitals from Google.
FAQ
Which three metrics belong to the Core Web Vitals?
Largest Contentful Paint (LCP, load perception), Interaction to Next Paint (INP, responsiveness) and Cumulative Layout Shift (CLS, visual stability).
Are Core Web Vitals a ranking factor?
Yes, as part of the page experience signals since 2021. Their weight is moderate - they mainly act as differentiation for comparably relevant pages.
What does INP have to do with FID?
INP replaced First Input Delay (FID) as the core web vital for responsiveness in March 2024 because it captures the entire interaction behaviour and not just the first input.
Where can I see my Core Web Vitals?
Most reliably in the Google Search Console (field data); additionally in PageSpeed Insights, Lighthouse and Chrome DevTools.