What Are Core Web Vitals? Site Speed in Plain Words
The short answer
Core Web Vitals are three measurements Google uses to describe how a web page feels to real visitors: how quickly the main content appears (Largest Contentful Paint, LCP), how quickly the page reacts to a tap or click (Interaction to Next Paint, INP), and how much the layout jumps around while loading (Cumulative Layout Shift, CLS).
Key takeaways
- A good result is an LCP within 2.5 seconds, an INP of 200 milliseconds or less and a CLS of 0.1 or less, for at least three in four visits.
- The scores come from real visitors over the previous 28 days, not from a single test.
- Google says Core Web Vitals are used by its ranking systems, and also that good scores do not guarantee a top position.
- Most fixes are developer work: lighter images, less script and reserved space.
In this guide
This guide is for business owners who have been told their website is slow, or who opened a speed report and saw red. It explains what Core Web Vitals are, what counts as a good result, how much they matter for ranking and where the fixes are. Fast pages are one part of our technical SEO service.
What are Core Web Vitals, in plain words?
They are Google's three measures of how a page feels to use. Each answers a question a visitor would ask.
| Measure | The visitor's question | Good | Needs improvement | Poor |
|---|---|---|---|---|
| Largest Contentful Paint (LCP) | How long until I can see the main content? | 2.5 seconds or less | Up to 4 seconds | Over 4 seconds |
| Interaction to Next Paint (INP) | When I tap or click, how quickly does the page react? | 200 milliseconds or less | Up to 500 milliseconds | Over 500 milliseconds |
| Cumulative Layout Shift (CLS) | Does the page stay still while I use it? | 0.1 or less | Up to 0.25 | Over 0.25 |
A page passes when it meets the good threshold on all three for at least 75 percent of visits, which Google calls the 75th percentile. Phones and desktop computers are measured separately.
LCP, INP and CLS explained
Largest Contentful Paint (LCP)
The time until a page's largest visible image, block of text or video has appeared. On an online furniture store's home page, that is likely to be the big photo at the top.
Interaction to Next Paint (INP)
How long the page takes to respond to clicks, taps and key presses, across the whole visit. Scrolling is not counted. If you tap Add to cart and nothing changes for half a second, that delay is what INP records.
Cumulative Layout Shift (CLS)
A score for how much visible content moves unexpectedly. If you go to tap a button and a banner loads above it, pushing the button down, that is a layout shift. Lower is better.
INP became a Core Web Vital in 2024, taking the place of an older measure called First Input Delay. A report that still mentions it is out of date.
Does site speed affect SEO?
Yes, to a degree. Core Web Vitals are part of how Google ranks pages, but they do not outweigh having the most relevant page.
Google states that Core Web Vitals are used by its ranking systems, and highly recommends good Core Web Vitals for success with Search. It also says that good results in the report do not guarantee that pages will rank at the top, and that Search always seeks to show the most relevant content, even if the page experience is below par.
Google adds that where many pages are helpful, a great page experience can contribute to success. Its pages give no figure for how much weight speed carries. A fair reading: speed will not rescue a page that does not answer the search, and it can help decide between pages that do.
How do you check your Core Web Vitals?
Use two free Google tools: PageSpeed Insights for a single page and Search Console for the whole site.
Check your scores
- Test one page in PageSpeed Insights
Enter the address of an important page. The first section shows what real visitors experienced over the previous 28 days and whether the page passes the Core Web Vitals assessment. Below it is a simulated test, which Google calls lab data. Judge the page by the real-visitor section when it is there.
- See the whole site in Search Console
The Core Web Vitals report groups pages that give a similar experience and labels each group Good, Need improvement or Poor, separately for mobile and desktop. Google's advice is to deal with Poor first and to share the report with whoever updates your site.
- If there is no data
A page with few visitors may not have enough real-visitor data. PageSpeed Insights then uses data for the whole site, and shows none if that is also too thin. Treat the simulated test as a guide.
How to speed up your website: where are the fixes?
Each measure has its own causes, so start with the one you fail. These come from Google's guidance for developers on web.dev.
| If you fail | Common causes | What to ask for |
|---|---|---|
| LCP (slow to show) | A slow server, large images, and styles or scripts that hold up the page | Smaller, compressed images in a modern format, no delayed loading on the main image and fewer blocking scripts |
| INP (slow to react) | Scripts that keep the browser busy for long stretches, and very large pages | Less script on each page, long tasks split up and a simpler page structure |
| CLS (jumps around) | Images, ads and embedded content with no size set, content added after loading, and web fonts | Width and height set on every image and video, space reserved for ads and embeds, and nothing new pushed in above existing content |
Fix templates, not single pages: a problem on one product page is usually on every page built from the same template. If images are the cause, read image SEO. Speed is one part of technical SEO, and our technical SEO checklist covers the rest.
Related serviceA speed plan your developers can follow
We test how your pages load and list the changes in order of how much they help, with a target for each.
See the serviceCommon questions about Core Web Vitals
What is a good PageSpeed Insights score?
Google's documentation says a score of 90 or above is considered good, 50 to 89 needs improvement and below 50 is poor. That score comes from the simulated test. It is separate from the Core Web Vitals assessment, which is based on real visitors.
Are Core Web Vitals measured on phones or on computers?
Both, and separately. Check the mobile results first: Google says it uses the mobile version of a site's content for indexing and ranking.
How long after a fix do Core Web Vitals improve?
Allow about a month. The real-visitor data covers the previous 28 days, so older visits take that long to drop out. In Search Console you can start a 28-day monitoring session to confirm the fix.
How much does it cost to fix Core Web Vitals?
It depends on the cause and on how the site is built. Taskcover's Technical SEO Audit, which reviews what Google can reach, list and load, starts from $2,500, one-time. Building the changes is priced separately unless it is part of your plan. See the pricing page.
Find out what is slowing your website down
Send us your website and we will show you how your pages load and what we would fix first, at no cost.
The authors
Who wrote and checked this guide
Written by
Jamiez Nguyen
Founder & CEO
Jamiez Nguyen founded Taskcover and leads strategy and client growth. He started it in 2017 as a team doing search work behind the scenes for other agencies, then opened it to businesses in the USA, Canada and Australia.
Reviewed by
John Edward
CTO
John Edward leads the technical side of Taskcover: how sites are built, how fast they load, and how search engines read them.
Updated Fact-checked About the people at Taskcover
Sources
Where the facts in this guide come from
Facts last checked on October 12, 2026.
- 1Understanding Core Web Vitals and Google search resultsGoogle Search CentralChecked on October 12, 2026
- 2Web Vitalsweb.dev (Google)Checked on October 12, 2026
- 3Core Web Vitals reportGoogle Search Console HelpChecked on October 12, 2026
- 4About PageSpeed InsightsGoogle for DevelopersChecked on October 12, 2026
- 5Largest Contentful Paint (LCP)web.dev (Google)Checked on October 12, 2026
- 6Interaction to Next Paint (INP)web.dev (Google)Checked on October 12, 2026
- 7Cumulative Layout Shift (CLS)web.dev (Google)Checked on October 12, 2026
- 8Understanding page experience in Google Search resultsGoogle Search CentralChecked on October 12, 2026
- 9Optimize Largest Contentful Paintweb.dev (Google)Checked on October 12, 2026
- 10Optimize Interaction to Next Paintweb.dev (Google)Checked on October 12, 2026
- 11Optimize Cumulative Layout Shiftweb.dev (Google)Checked on October 12, 2026
- 12Mobile site and mobile-first indexing best practicesGoogle Search CentralChecked on October 12, 2026
