What are Core Web Vitals
Also known as: Web Vitals, page experience metrics, LCP, INP and CLS
Core Web Vitals are three metrics that measure the real experience of people visiting a page: LCP, how long the largest content takes to appear; INP, how quickly the page responds to clicks and taps; and CLS, how much the layout moves while loading. Google recommends an LCP within 2.5 seconds, an INP of 200 milliseconds or less and a CLS of 0.1 or less, and uses these metrics in its ranking systems.
Passing page = LCP ≤ 2.5 s and INP ≤ 200 ms and CLS ≤ 0.1, at the 75th percentile of visits
The 75th percentile means at least 3 out of 4 visits must be within the threshold. Mobile and desktop are assessed separately.
A landing page opens with a 1.8 MB photo at the top. On phones, LCP is 4.1 seconds. A promo badge loads after the text and pushes the button down, and CLS reaches 0.25.
The team compresses the photo, uses a modern format and gives it loading priority; LCP drops to 2.1 seconds. It reserves space for the badge in the layout; CLS drops to 0.02. The page passes both metrics and the button stops escaping the visitor's finger.
The three metrics
| What it measures | Good | |
|---|---|---|
| LCP (Largest Contentful Paint) | Loading: when the largest visible element appears | 2.5 seconds or less |
| INP (Interaction to Next Paint) | Responsiveness: how long the page takes to react to a click or tap | 200 milliseconds or less |
| CLS (Cumulative Layout Shift) | Stability: how much content moves on its own | 0.1 or less |
Where the numbers come from
There are two kinds of measurement. Lab data simulates a visit on a set machine and connection, and is used for diagnosis. Field data comes from real visits by people using Chrome, gathered in the CrUX (Chrome UX Report) dataset.
Search Console's Core Web Vitals report uses field data: for each group of pages, it shows the value 75% of visits reached over the last 28 days. Low traffic sites may not have enough data, and the report says so when that happens.
INP replaced FID
The original responsiveness metric was FID (First Input Delay), which only measured the delay of the first interaction. INP was created to cover responsiveness across the whole visit, became a pending metric in 2023 and a stable Core Web Vital in 2024, replacing FID.
According to web.dev, stable metrics do not change more than once a year, and any change is announced in advance. Any guide that still talks about FID is out of date.
How much they weigh in ranking
Google confirms that Core Web Vitals are used by its ranking systems, with two caveats. First, good numbers do not guarantee the top spot, and chasing a perfect score just for SEO may not be the best use of time. Second, Search always tries to show the most relevant content, even when page experience is poor.
In practice, experience is a tiebreaker. When lots of helpful content competes for the same search, a fast, stable page has the edge. And the most direct gain is often outside SEO: a slow page loses visitors before they read the offer.
How to improve each one
- LCP: a light main image in a modern format with loading priority; a fast responding server; nothing blocking rendering at the top.
- INP: less heavy JavaScript, long tasks split into smaller pieces and third party scripts loaded only when needed.
- CLS: width and height set on images and videos, reserved space for ads, banners and embeds, and fonts that do not make text jump when loading.
Frequently asked questions
What are Core Web Vitals?
Three Google metrics that measure the real experience on a page: LCP for loading, INP for responsiveness and CLS for visual stability.
What are good values?
LCP of 2.5 seconds or less, INP of 200 milliseconds or less and CLS of 0.1 or less, reached by at least 75% of visits, on mobile and desktop.
Do Core Web Vitals affect ranking?
Yes, Google uses these metrics in its ranking systems. But good numbers do not guarantee the top spot, and content relevance still weighs more.
Where can I measure Core Web Vitals?
In Search Console's Core Web Vitals report, with real visit data, and in PageSpeed Insights, which shows field and lab data for a page.
What happened to FID?
It was retired. In 2024 INP took its place as the responsiveness metric, because it measures every interaction in a visit, not just the first.
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Rodrigo Fávaro
Founder of ROO3, a marketing and technology agency in São José do Rio Preto, Brazil. Builds AI products running in production (Tobia, gerar.app, Pense Mercado) and maintains the AI Benchmark, a public ranking of AI models.
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