What Are Core Web Vitals?
Written by Anthony Eneje · Head of SEO & AI SearchWritten by Anthony Eneje · Head of SEO & AI Search
Core Web Vitals are three metrics Google uses to measure real user experience on your web pages: Largest Contentful Paint (loading), Interaction to Next Paint (responsiveness) and Cumulative Layout Shift (visual stability). They matter because they are part of Google's ranking systems, and because slow, janky pages lose visitors and sales regardless of what Google thinks.
This guide explains each Core Web Vitals metric in plain English, the scores you need, how to measure Core Web Vitals for free, and the fixes that actually move the numbers.
LCP measures loading: how long it takes for the biggest visible element on the page, usually a hero image or headline, to appear. Google's threshold for a good LCP is 2.5 seconds or less. Slow server response times, oversized images and render-blocking scripts are the usual suspects when LCP is poor.
INP measures responsiveness: the delay between a user interaction, such as a tap or click, and the next visual update on screen. A good INP is 200 milliseconds or less. INP replaced the older First Input Delay (FID) metric in 2024 because FID only measured the first interaction, while INP watches them all. Heavy JavaScript is almost always the cause of a poor INP.
CLS measures visual stability: how much the page jumps around while loading. Everyone has tried to tap a button that moved at the last second. That is a layout shift. A good CLS score is 0.1 or less, and the fix is usually reserving space for images, ads and embeds before they load.
Core Web Vitals are a confirmed part of Google's page experience system, which means they influence rankings. Be realistic about the size of that influence: they act more like a tiebreaker than a trump card. Brilliant content with mediocre vitals can still outrank thin content with perfect scores.
The bigger reason to care is your visitors. Google's research has repeatedly shown that as load time grows, the probability of the visitor leaving grows with it. A poor user experience costs you enquiries and sales directly, before rankings enter the picture. When we rebuild sites at Rank Craft, hitting green Core Web Vitals is part of the build spec, not an optimisation bolted on later.
You can check Core Web Vitals for free in three places, and it is worth understanding the difference between them:
One caution: lab data and field data often disagree, because a lab test is one simulated visit while field data is thousands of real ones on real phones and real connections. Field data wins every argument. Judge your site by what real users experience.
The right fix depends on which metric is failing, but these cover most cases we see in audits:
Measure first, fix what the data names, then measure again. Field data updates over a rolling 28-day window, so give real improvements a month to show in the Core Web Vitals report.
Treat Core Web Vitals as table stakes, not a growth strategy. Get all three metrics green, because it removes a ranking handicap and stops you losing the visitors you already earn. Then put your energy into the things that actually build rankings: content that answers real searches, technical health, and authority. If your scores are deep in the red and you are not sure why, that is exactly the kind of thing our SEO team untangles every week, and an audit will tell you in days what guessing would take months to find.
Yes, Core Web Vitals are a confirmed Google ranking signal as part of the page experience system. They are a tiebreaker rather than a dominant factor: great content with poor vitals can still rank, but between two similar pages, the better user experience tends to win.
Yes. PageSpeed Insights, Google Search Console's Core Web Vitals report, and Chrome's built-in Lighthouse tool are all free. Search Console is the best starting point because it shows real user field data across your whole site.
Google's thresholds are: LCP under 2.5 seconds, INP under 200 milliseconds, and CLS under 0.1. Aim to hit those for at least 75% of visits, measured with real user data rather than lab tests.
Anthony leads SEO and AI search at Rank Craft. He plans and runs the ranking campaigns behind our client results, and spends most of his week inside search data, site audits and AI visibility testing. More articles by Anthony.