What are Core Web Vitals
Core Web Vitals are three metrics Google uses to measure how good a site's experience is: loading speed (LCP), responsiveness (INP) and layout stability (CLS).
LCP measures how fast the main content appears. INP measures how fast the page responds to a click. CLS measures how much elements jump around while loading.
Together the three tell how smooth and comfortable a site is to use.
Why Core Web Vitals matter
Core Web Vitals are an official Google ranking factor. They are not the most important one, but between two otherwise equal pages the faster one has the edge. They also affect conversion directly.
The three metrics and their thresholds
Google has set a boundary for each metric beyond which the result counts as good. The assessment is based on data from real visitors, not on a single test.
- LCP (Largest Contentful Paint): the largest visible element, usually the hero image or headline, should appear within 2.5 seconds.
- INP (Interaction to Next Paint): the page should respond to a click or tap within 200 milliseconds. INP replaced the older FID metric in March 2024.
- CLS (Cumulative Layout Shift): the combined layout shift score should stay at or below 0.1.
Lab data versus field data
PageSpeed Insights shows two different things. The upper block is data from real Chrome users over the last 28 days, and that is what Google uses for the assessment. The lower block is a lab test, a one-off simulation that helps find causes.
A small Estonian company site often has too few visitors for field data to be collected, and the report says there is not enough data. That is not an error. In that case you rely on the lab test and on checking the site on your own phone.
Example: what slows down a small site
A typical case: a cafe's hero photo was uploaded straight from the camera and weighs several megabytes, fonts come from an external service, and the bottom of the page carries a chat widget, a map and a social feed. LCP suffers because of the photo, INP because of the extra scripts.
CLS is most often spoiled by an image or banner with no space reserved in the code: the text is already on screen, then the image loads and pushes everything down. A cookie notice that appears late does the same.
How to check and what to fix
Enter your address in PageSpeed Insights and look at the mobile result, which is usually the weaker one. The Core Web Vitals report in Google Search Console shows which groups of pages need attention.
The fixes with the biggest effect tend to be simple: resize images and serve them in a modern format, give images explicit dimensions, remove scripts you do not need and move to faster hosting.
Frequently asked questions
What counts as a good Core Web Vitals result?
A page passes when at least 75 percent of visits have an LCP of 2.5 seconds or less, an INP of 200 milliseconds or less and a CLS of 0.1 or less. All three have to be met at once.
Do I need a PageSpeed score of 100?
No. The score is a summary of the lab test, not what Google uses for ranking. It matters more that the three core metrics are in the green and the site feels fast on a phone.
Will good Core Web Vitals put my site first on Google?
Not on their own. A fast page without relevant content will not rank high. Speed gives an edge when content and trust are on par with competitors, and it helps keep visitors on the page either way.