Websites for UK businesses, explained
Core Web Vitals Explained: What the Scores Mean
7 November 2026
Core Web Vitals are three measurements Google uses to judge how a page feels to real visitors: how fast the main content loads, how quickly the page responds when someone taps or clicks, and how much the layout jumps about. Here are Core Web Vitals explained, with what the scores mean and where to check yours.
Quick answer: The three Core Web Vitals are Largest Contentful Paint (good: 2.5 seconds or less), Interaction to Next Paint (good: 200 milliseconds or less) and Cumulative Layout Shift (good: 0.1 or less). Each is judged at the 75th percentile of real page visits, separately for mobile and desktop.
Key Takeaways
LCP measures loading; a good score is 2.5 seconds or less.
INP measures responsiveness; a good score is 200 milliseconds or less.
CLS measures visual stability; a good score is 0.1 or less.
Scores are judged at the 75th percentile of page visits, for mobile and desktop separately.
INP replaced First Input Delay as a Core Web Vital in 2024.
The three measurements
Largest Contentful Paint (LCP)
LCP measures loading. It's the time it takes for the largest image or block of text in the visible part of the page to appear. A good LCP is within 2.5 seconds of the page starting to load.
Interaction to Next Paint (INP)
INP measures responsiveness: how long the page takes to react visibly after someone clicks, taps or types. A good INP is 200 milliseconds or less. INP became a stable Core Web Vital in 2024, replacing First Input Delay.
Cumulative Layout Shift (CLS)
CLS measures visual stability, meaning how much content moves around unexpectedly while the page loads. You'll know the feeling if you've ever gone to tap a button and an advert pushed it down the page. A good CLS is 0.1 or less.
What Core Web Vitals scores mean
Google's web.dev sets three bands for each measurement.
Measurement | Good | Needs improvement | Poor |
|---|---|---|---|
Largest Contentful Paint | 2.5 seconds or less | Over 2.5 up to 4 seconds | Over 4 seconds |
Interaction to Next Paint | 200 ms or less | Over 200 up to 500 ms | Over 500 ms |
Cumulative Layout Shift | 0.1 or less | Over 0.1 up to 0.25 | Over 0.25 |
The 75th percentile rule
Each score is judged at the 75th percentile of page visits, with mobile and desktop measured separately. In practice, a page passes when at least three out of four visits get a good result on all three measurements.
That's why a page can feel quick on your office broadband but still fail: the score reflects your real visitors, many of whom are on phones and mobile data.
Do Core Web Vitals affect rankings?
Google says that good Core Web Vitals, along with other page experience aspects, align with what its core ranking systems seek to reward, and it highly recommends achieving them. Relevant, helpful content still comes first, but a slow, jumpy page makes it harder for that content to do its job.
Where to check your scores
Google Search Console has a Core Web Vitals report showing how your pages perform for real visitors, grouped into good, needs improvement and poor.
Google's PageSpeed Insights tests a single page and shows the same three measurements, along with suggestions.
Start with the pages that matter most to your business, such as your homepage, your main service pages and your contact page.
Common causes and fixes
Slow LCP
The usual cause is a large hero image or slow hosting. Resize and compress images, use modern formats such as WebP, and ask your host about server response times.
Poor INP
Heavy scripts are the common culprit, including chat widgets, tracking tags and page builders. Remove anything you don't use. Our guide to cookie banners and the UK rules is a good prompt to review which third-party tools your site loads.
High CLS
Images without set dimensions, late-loading adverts and banners that push content down all cause layout shift. Give images a width and height, and reserve space for anything that loads late.
Speed, security and accessibility go together
A fast site should also be a secure one. If your pages don't load over HTTPS yet, our guide to SSL certificates explains how to switch.
Many fixes that help Core Web Vitals, such as clear layouts and big enough buttons, also help disabled visitors. Our guide to website accessibility law explains the standard to aim for.
Page speed is one of six essentials in our business website checklist.
If you have a question, get in touch with our team.
There is more advice on our blog.
Frequently asked questions
What is a good Core Web Vitals score?
An LCP of 2.5 seconds or less, an INP of 200 milliseconds or less and a CLS of 0.1 or less, each at the 75th percentile of visits.
Why does my site pass on desktop but fail on mobile?
Mobile and desktop are measured separately, and phones often have slower connections and processors, so heavy pages tend to struggle there first.
What happened to First Input Delay?
Interaction to Next Paint replaced First Input Delay as a Core Web Vital in 2024.
Do I need a developer to fix Core Web Vitals?
Not always. Compressing images and removing unused plugins or widgets often helps. Script and hosting problems may need a developer.
Your next step
Open Search Console's Core Web Vitals report, or run your homepage through PageSpeed Insights, and note which of the three measurements needs work.
For the full definitions of each measurement, read web.dev's guide to Core Web Vitals.