Core Web Vitals, explained like a human
LCP, INP and CLS are just Google measuring what visitors already feel: the wait, the laggy taps, the page jumping about. Here is what each means, and how we get all three green.
What LCP, INP and CLS actually measure
Forget the acronyms for a second. Each vital maps to a moment you have experienced on someone else's slow website.
LCP: the wait for the main thing
Largest Contentful Paint is how long before the biggest element, usually your hero image or headline, is on screen. The restaurant test: not when the door opened, when the food arrived. Good is 2.5 seconds or less.
INP: the lag when you tap
Interaction to Next Paint is how quickly the page visibly responds to a tap. A light switch with a delay: 200ms feels instant, half a second feels broken. Good is 200ms or less.
CLS: the page that will not sit still
Cumulative Layout Shift scores how much things move after appearing: you reach for a button and an image shoves it down the page. Good is 0.1 or less, and zero is achievable.
Core Web Vitals thresholds, and where to see yours
Google grades every metric into three bands, using data from real Chrome visitors over a rolling 28 days. A page passes when at least 75% of visits land in the good band.
| Metric | Good | Needs improvement | Poor |
|---|---|---|---|
| LCP (loading) | 2.5s or less | 2.5s to 4s | Over 4s |
| INP (responsiveness) | 200ms or less | 200ms to 500ms | Over 500ms |
| CLS (visual stability) | 0.1 or less | 0.1 to 0.25 | Over 0.25 |
Where to see your scores
Open Google Search Console and find the Core Web Vitals report in the page experience section: your pages grouped into good, needs improvement and poor, mobile and desktop separately. Mobile is where most sites fail. Our free page speed checker runs a Lighthouse test on any page in about a minute.
Why "failing" matters
Core Web Vitals have been part of Google's ranking signals since 2021, so a failing page gives up ground to every comparable competitor that passes. The bigger half of the problem is human: Google's research found 53% of mobile visitors abandon a page taking over 3 seconds. A poor LCP is your advertising budget paying for visits that leave before the page exists.
How we fix each vital, specifically
LCP under 2.5s: content first, everything else after
Fixing LCP: make the main thing arrive sooner
A slow LCP is nearly always a heavy hero element on a slow pipeline. We convert images to WebP, preload the LCP image, clear the render-blocking scripts queued in front of it and tune the server so the first byte arrives fast. Full detail on our page speed optimisation page.
- Hero images compressed, resized and served as WebP
- Render-blocking CSS and JavaScript cleared out of the way
- Server response and caching tuned to cut TTFB
INP under 200ms: taps that feel instant
Fixing INP: stop JavaScript hogging the main thread
Laggy interactions come from JavaScript doing too much at once: analytics, chat widgets and plugins all fighting for the thread your tap needs. We defer and split heavy scripts, remove what nothing uses, and on WordPress trim the plugin stack behind most of it: see our WordPress speed optimisation service.
- Third-party scripts delayed until the page is interactive
- Long JavaScript tasks split so taps get processed promptly
- Plugin bloat identified with data, then removed
CLS at 0.1 or less: pages that hold still
Fixing CLS: reserve the space before it loads
Layout shift is the easiest vital to eliminate completely, because it is almost always missing measurements: images without dimensions, embeds with no reserved space, fonts swapping in at a different size. We fix all three, and once fixed CLS tends to stay fixed, benefiting rankings alongside the wider technical SEO picture.
- Width and height set on every image and embed
- Space reserved for banners, ads and dynamic content
- Fonts preloaded with size-matched fallbacks to stop the swap jolt
Is your website slower than your competitors?
Run a real Lighthouse speed test free. See your scores and the exact fixes that would make your site faster.
Fixed once, or kept green permanently
The one-off fix gets you passing. The retainer keeps you passing as content, plugins and Google all keep changing. Prices exclude VAT.
Website Speed Fix
One-off deep optimisation. Most sites reach 90+ on Lighthouse mobile.
£349 one-off
- Full performance audit first
- Images, caching, scripts and fonts optimised
- Core Web Vitals: LCP, INP and CLS fixed
- Hosting-level tuning where possible
- Before and after report
- Measurable improvement or your money back
Speed Retainer
Continuous speed optimisation and Core Web Vitals protection.
£89 /month
£890 /year
- Monthly Lighthouse and CrUX review
- Core Web Vitals kept green in Search Console
- Image and script optimisation ongoing
- Plugin bloat control
- Monthly performance report
- Regression fixes included
All prices exclude VAT. Cancel monthly plans any time. Secure card and Direct Debit payments powered by Stripe.
Frequently asked questions
What are Core Web Vitals in simple terms?
Core Web Vitals are three measurements Google takes from real Chrome users on your website: how quickly the main content appears (LCP), how fast the page reacts when someone taps (INP), and how much the layout jumps around while loading (CLS). They are Google's scorecard for whether your site feels fast and stable to real visitors.
What replaced FID in Core Web Vitals?
Interaction to Next Paint (INP) replaced First Input Delay (FID) in March 2024. FID only measured the delay before your first tap was processed; INP is stricter, measuring responsiveness across every interaction in the visit. Sites that comfortably passed FID often fail INP, which is why many pass rates dropped that year.
Where can I check my Core Web Vitals?
Google Search Console is the definitive place: its Core Web Vitals report shows how real users experienced your pages over the previous 28 days, grouped into good, needs improvement and poor. PageSpeed Insights shows the same field data for one page alongside a lab test, and our free checker gives a quick Lighthouse view.
What is a good LCP, INP and CLS score?
Google's thresholds for a good experience are an LCP of 2.5 seconds or less, an INP of 200 milliseconds or less, and a CLS of 0.1 or less. At least 75% of real visitors must be inside the threshold to pass, so your slowest customers on 4G phones decide the score, not a fast office computer.
Do Core Web Vitals affect Google rankings?
Yes, they have been part of Google's ranking signals since 2021. They act as a tiebreaker: strong content on a failing page can still rank, but between comparable pages the faster one gets the edge. The bigger cost is human: Google research found 53% of mobile users abandon pages taking over 3 seconds.
Why does PageSpeed Insights disagree with Search Console?
They show different things. Search Console reports field data: measurements from your real visitors over 28 days. PageSpeed Insights adds a fresh lab test on simulated hardware, and the two rarely match. Field data is what counts for ranking; lab data is what engineers use to reproduce and fix the causes.
How much does it cost to fix Core Web Vitals?
Our Website Speed Fix is £349 excluding VAT: a full audit, then targeted fixes for LCP, INP and CLS, with a before and after report and money back if nothing measurably improves. The £89 a month Speed Retainer keeps all three green as your content and plugins change.