Core Web Vitals are three measurements of real-user page experience: Largest Contentful Paint (loading, 2.5 seconds or less), Interaction to Next Paint (responsiveness, 200 milliseconds or less) and Cumulative Layout Shift (visual stability, 0.1 or less). Google measures them at the 75th percentile of visits.
What are the three Core Web Vitals?
The thresholds below come from Google's web.dev guide to Web Vitals and its Search documentation.
| Metric | What it measures | Good |
|---|---|---|
| Largest Contentful Paint (LCP) | How fast the main content appears | 2.5 seconds or less |
| Interaction to Next Paint (INP) | How quickly the page reacts to clicks, taps and key presses | 200 milliseconds or less |
| Cumulative Layout Shift (CLS) | How much the layout jumps while loading | 0.1 or less |
What happened to First Input Delay?
INP replaced First Input Delay (FID) as a Core Web Vital and became stable in 2024, according to web.dev. If an older guide lists FID, it is out of date. INP is stricter because it looks at the responsiveness of interactions across the visit, not only the first one.
What does "75th percentile" mean?
Google recommends judging each metric at the 75th percentile of page loads, split by mobile and desktop. In plain terms, a page passes a metric when at least three out of four visits meet the "good" threshold. One fast test on your own laptop does not tell you that.
Do Core Web Vitals affect rankings?
Yes, but modestly and alongside other signals. Google says it highly recommends good Core Web Vitals for success with Search and that they align with what its core ranking systems seek to reward. Its documentation does not say how much they weigh against relevance. Treat them as a floor: poor scores can hold a page back and good scores will not rescue a page that does not answer the query. For the reading and indexing basics that come first, see how to check if a page is indexed by Google.
Where do you check your scores?
Start with the Core Web Vitals report in Google Search Console. Google points to it as the place that shows how your pages perform, grouped by status. It uses real visit data, which is the data that counts. Lab tools such as Lighthouse help you find the cause, but they simulate one visit.
- Open the Core Web Vitals report and find the groups marked Poor or Needs improvement.
- Pick one URL from the largest group, since fixes usually apply to a whole template.
- Test that URL in a lab tool to see what is slow.
- Fix the cause, then wait for field data to update before judging the result.
Common causes and first fixes
Slow LCP
The largest element is usually a hero image or headline block. Common causes are a large uncompressed image, a slow server response and render-blocking scripts or styles. Serve a right-sized image and avoid lazy-loading the one above the fold.
Poor INP
Long JavaScript tasks block the page from reacting. Remove scripts you do not need, delay third-party tags until after interaction and split heavy work into smaller pieces.
High CLS
Layout shifts come from images and embeds without set dimensions, late-loading ads and web fonts swapping in. Reserve space with width and height attributes and fixed containers.
How much effort is worth it?
If Search Console shows your pages as good, stop and spend the time on content. If a template is marked Poor, fix it, because one change helps every page on it. Speed work sits within the wider crawl and index checks in do you need an XML sitemap and canonical URLs. Nightcrop's audit runs a set of technical checks on your site, and Core Web Vitals are one more reading to compare against.
Frequently Asked Questions
What are the Core Web Vitals thresholds?
LCP of 2.5 seconds or less, INP of 200 milliseconds or less and CLS of 0.1 or less, each measured at the 75th percentile.
Is INP the same as FID?
No. INP replaced FID and covers the responsiveness of interactions over the whole visit, so it is harder to pass.
Are Core Web Vitals a ranking factor?
They are part of the page experience signals Google's ranking systems consider. Google does not say how much they weigh, and relevance still comes first.
Why do my lab scores differ from Search Console?
Lab tools simulate one visit on one device. Search Console reports data from real visits, which vary by device and connection.
How long until a fix shows in Search Console?
Field data is collected over time, so expect a delay of weeks rather than days before the report fully reflects a fix.