# What are Core Web Vitals, and how do I pass them?

> Core Web Vitals are three measures of real page experience: Largest Contentful Paint (LCP, loading), Interaction to Next Paint (INP, responsiveness) and Cumulative Layout Shift (CLS, visual stability). Google's “good” thresholds, at the 75th percentile of visits, are LCP 2.5 seconds or less, INP 200 milliseconds or less and CLS 0.1 or less. They are a real but lightweight ranking factor.

Topic: Technical SEO. Last reviewed: 12 November 2026. Source: Arcline, https://arcline.celira.space/faq/core-web-vitals

## What are the three Core Web Vitals?

Core Web Vitals are Google's three measures of how a page feels to real visitors: how fast the main content appears, how quickly the page reacts to a tap or click, and whether things jump around while loading. A page is judged at the 75th percentile of real visits, so three visits in four must meet the target, with mobile and desktop measured separately. INP replaced the older First Input Delay metric in March 2024.

| Metric | What it measures | Good | Needs improvement | Poor |
| --- | --- | --- | --- | --- |
| LCP (Largest Contentful Paint) | Loading: when the largest visible element, often a hero image or heading, appears | 2.5 s or less | 2.5 to 4 s | Over 4 s |
| INP (Interaction to Next Paint) | Responsiveness: how long the page takes to react after a tap, click or key press | 200 ms or less | 200 to 500 ms | Over 500 ms |
| CLS (Cumulative Layout Shift) | Visual stability: how much content moves unexpectedly | 0.1 or less | 0.1 to 0.25 | Over 0.25 |

## How do you test and measure Core Web Vitals?

1. Paste a page address into PageSpeed Insights. The top section shows real-user (field) results and whether the page passes the Core Web Vitals assessment.
2. In Search Console, open the Core Web Vitals report. It groups your URLs as good, needs improvement or poor, for mobile and desktop, so you can fix a whole group of similar pages at once.
3. Use the lab results lower on the PageSpeed Insights page, and Lighthouse in Chrome's developer tools, to find out why a page is slow. Re-test after each change.

Field data comes from real Chrome users over roughly the previous 28 days, and it is what Google's assessment uses. Lab data is one simulated load on a fixed device and connection: repeatable and good for debugging, but different from reality, and it estimates responsiveness with a proxy (Total Blocking Time) because nobody interacts with the test. Small sites often lack enough traffic for page-level field data, and PageSpeed Insights then shows site-wide data or none.

## How much do Core Web Vitals affect rankings?

A little, and less than the hype suggests. Google's ranking systems do use Core Web Vitals as part of page experience, but Google also says relevance comes first: a slightly slow page with the best answer can outrank a fast page with a weak one. Treat them as a lightweight ranking factor that can help when pages are otherwise close, and cannot rescue a page that does not answer the question.

The bigger reason to care is people. A page that takes five seconds to show its main content, then shifts as someone reaches for a button, loses visitors and enquiries whatever Google does. Passing the thresholds does not guarantee better rankings, so see [how to improve your Google ranking](https://arcline.celira.space/faq/improve-google-ranking) for what usually matters more.

## How do you fix a slow LCP?

- Resize and compress the main image. A 4,000-pixel photo shown 800 pixels wide wastes seconds. Save it at the size shown, in a modern format such as WebP or AVIF.
- Do not lazy-load the main image at the top of the page. Load it first, and lazy-load only images further down.
- Check your server response time. About 0.8 seconds or less is a good target. Slow hosting or a missing cache is a common cause of more, and a CDN helps distant visitors.
- Trim render-blocking CSS and scripts, and limit fonts: one or two families, only the weights you use, and `font-display: swap` so text appears at once.

## How do you fix INP and CLS?

- **INP:** remove third-party scripts you do not need, such as a second chat widget, extra trackers or an unused slider, because they are the most common cause of sluggish clicks. Load the rest after the page is usable.
- **CLS, images and embeds:** give every image, video and embed a width and height, or an aspect ratio, so space is reserved before it loads.
- **CLS, late content:** reserve room for ads, cookie banners and widgets, and do not insert content above what a visitor is already reading.
- **CLS, fonts:** choose a fallback font close in size to your web font so text does not reflow when the font loads.

## What should a small site do first?

1. Test your home page and your three most important pages in PageSpeed Insights, and note which metric fails.
2. Fix the heaviest image first, then remove or delay one third-party script.
3. Re-test. Field data takes about a month to reflect a change, so lab results are your quick check.

Arcline [times your key pages](https://arcline.celira.space/features) with Google's PageSpeed test, shows how long the main content takes, how fast the page reacts and how much it moves when real-visitor data exists, and flags a page that gets noticeably slower. Speed fixes that live in your theme or host are jobs it cannot do for you, so it gives exact steps instead. For the wider checklist, see [what an SEO audit checks](https://arcline.celira.space/faq/seo-audit).

## Related questions

- [How can I improve my website's Google ranking?](https://arcline.celira.space/faq/improve-google-ranking.md)
- [What is an SEO audit, and what does a free SEO audit check?](https://arcline.celira.space/faq/seo-audit.md)
- [How can a small business do SEO without hiring an agency?](https://arcline.celira.space/faq/seo-for-small-business.md)
- [What is SEO and how does it work?](https://arcline.celira.space/faq/what-is-seo.md)