What are Core Web Vitals? A plain-English guide
Core Web Vitals are three numbers Google uses to measure how a page feels to real visitors: how fast the main content loads, how quickly it responds to a tap, and whether it stays still while loading. Google measures them from real Chrome users over the last 28 days.
Here’s what each one means, the scores you need, where to see yours, and what usually fixes them, without the developer jargon.
The three Core Web Vitals and their passing scores
A page passes when all three are in the good range for at least 75% of visits, checked separately for phones and computers.
| Metric | What it measures | Good | Needs work | Poor |
|---|---|---|---|---|
| Largest Contentful Paint (LCP) | How long until the main content, usually the top photo or headline, appears | 2.5 s or less | 2.5 to 4 s | Over 4 s |
| Interaction to Next Paint (INP) | How quickly the page reacts when someone taps a button or opens the menu | 200 ms or less | 200 to 500 ms | Over 500 ms |
| Cumulative Layout Shift (CLS) | How much the page jumps around while it loads | 0.1 or less | 0.1 to 0.25 | Over 0.25 |
INP replaced the older First Input Delay (FID) in 2024. If a guide still talks about FID, it’s out of date.
What each one feels like to a customer
Forget the acronyms for a moment. This is what a visitor on a phone actually notices.
Loading (LCP): “Is anything happening?”
They tap your link and stare at a blank or half-built page. Past a few seconds, many give up and go back to the search results.
Responding (INP): “Did that work?”
They tap the menu or the call button and nothing happens for a moment, so they tap again, or leave. Heavy scripts are the usual cause.
Staying still (CLS): “I didn’t mean to tap that!”
They go to tap “Call” and a late-loading banner pushes the page down, so they hit something else. It feels sloppy and untrustworthy.
Where to see your Core Web Vitals
There are two kinds of results, and it helps to know which you’re looking at.
Real visitors (field data)
Collected from Chrome users who share usage statistics, over the last 28 days. This is what Google uses for Search. It appears at the top of PageSpeed Insights and in Search Console.
A single test (lab data)
One simulated load on a mid-range phone, run when you click the button. It gives the 0 to 100 score and the list of problems. Our free speed test runs this and explains it in plain English.
“Not enough data”
Small or new sites often don’t have enough real-visitor data yet. That’s normal. Use the lab test to find and fix problems in the meantime.
Search Console’s report
Groups similar pages together and rates each group by its worst number. After a fix, click Start tracking and Google checks the next 28 days.
What usually fixes each one
On small business sites, the same few causes come up again and again.
Slow loading (LCP)
Shrink the top photo, load it first instead of lazy-loading it, replace sliders and video backgrounds with one image, and turn on your host’s caching or CDN.
Slow responding (INP)
Remove plugins, apps and widgets you don’t need, especially chat bubbles, review feeds and tracking tags. Each one adds code the phone has to run.
Jumping around (CLS)
Give every image and embed a set width and height, reserve space for banners, and avoid popups that appear after the page loads.
Still stuck?
If the platform itself is heavy, tweaks only go so far. Our guide to why your website is slow walks through the 8 most common causes in order.
How much do they matter for Google?
Enough to fix, not enough to obsess over.
They’re part of page experience
Google says good Core Web Vitals line up with what its ranking systems reward, and recommends site owners reach good scores.
Content still comes first
A fast page with thin content won’t beat a helpful page from a trusted business. Speed helps you compete; it doesn’t replace being relevant.
Customers feel it either way
Even apart from rankings, a page that loads fast and stays still is easier to call from. That’s the payoff that shows up in your phone log.
Good enough is good enough
Once all three are green, chasing a perfect 100 rarely changes much. Spend the time on content and reviews instead.
Core Web Vitals questions
What are the three Core Web Vitals?
Largest Contentful Paint (LCP) measures how fast the main content shows up. Interaction to Next Paint (INP) measures how quickly the page responds when someone taps or clicks. Cumulative Layout Shift (CLS) measures how much the page jumps around while it loads.
What are good Core Web Vitals scores?
LCP of 2.5 seconds or less, INP of 200 milliseconds or less, and CLS of 0.1 or less. Google measures these at the 75th percentile of real visits, so most of your visitors need a good experience, not just the average.
Do Core Web Vitals affect Google rankings?
They are part of what Google calls page experience, which its ranking systems are built to reward. Google recommends good scores for success in Search, but helpful, relevant content still matters most.
Why does PageSpeed say there isn’t enough data for my site?
Real-visitor data comes from Chrome users who share usage statistics. Small or new sites often don’t have enough visits to report. Google then shows only the lab test, which is still useful for finding problems.
Is the PageSpeed score the same as passing Core Web Vitals?
No. The 0 to 100 score comes from a single lab test on a simulated phone. Core Web Vitals come from real visitors over the last 28 days. A site can score well in one and not the other, so check both.
What happened to First Input Delay (FID)?
Interaction to Next Paint (INP) replaced First Input Delay as a Core Web Vital in 2024. INP looks at how quickly the page responds to taps and clicks throughout the visit, not just the first one.
How long does it take for fixes to show up?
The lab test updates as soon as you run it again. Real-visitor numbers in PageSpeed and Search Console cover the last 28 days, so improvements show up gradually over about a month.
Sources, checked November 2026: web.dev: Web Vitals · Search Console Help: Core Web Vitals report · Google Search Central: Core Web Vitals and Search · web.dev: optimize LCP.
Related guides: Why is my website so slow? · Free website speed test · Why isn’t my website getting calls? · All guides
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