Guide · Building & launching
Core Web Vitals explained for business owners
Core Web Vitals are three measurements Google uses to describe how a page feels to real visitors: how quickly the main content appears, how quickly the page responds when you tap or click, and whether the layout jumps around while loading. They matter because slow and unstable pages lose visitors, and because they are part of the page experience signals Google considers. This guide explains them without technical jargon.
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In short
In short
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LCP (Largest Contentful Paint) — how long until the main content is visible. Google's "good" threshold is 2.5 seconds or less.
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INP (Interaction to Next Paint) — how quickly the page responds to taps, clicks and typing. "Good" is 200 milliseconds or less.
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CLS (Cumulative Layout Shift) — how much the layout moves unexpectedly. "Good" is 0.1 or less.
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Google evaluates these on real visitors' data, at the 75th percentile, mostly from mobile devices.
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The biggest improvements usually come from images, third-party scripts and server response time.
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Guide
The three metrics
LCP: loading
LCP measures the time until the largest visible element — usually a hero image, a video poster or a large heading — is displayed. Visitors perceive this as "the page has loaded". Slow servers, large images, render-blocking scripts and fonts delay it.
INP: responsiveness
INP measures the delay between a visitor's interaction and the next visual update, across the visit. A page may look loaded but feel frozen when a menu or button is tapped because the browser is busy running scripts. INP replaced the earlier First Input Delay metric in March 2024.
CLS: visual stability
CLS measures unexpected movement of content: a button shifting as an image above it loads, a banner pushing text down, a font swap changing line breaks. It causes mis-taps and frustration.
Thresholds and definitions are published by Google at web.dev/articles/vitals.
Where to see your data
- Search Console → Core Web Vitals report: groups of your pages as good, needs improvement or poor, based on real Chrome users.
- PageSpeed Insights: field data for a URL or origin when there is enough traffic, plus a lab test with diagnostics.
- Your own measurement: some analytics setups collect these metrics from all visitors.
Sites with little traffic may not have field data; lab tests then give an approximation.
What usually helps most
For LCP
- Compress and resize the main image; use modern formats; do not lazy-load the image in the first screen.
- Reduce server response time with caching and a CDN.
- Remove or defer scripts and styles that block rendering.
For INP
- Reduce the amount of JavaScript, especially from third-party tags, chat widgets and trackers.
- Break long tasks into smaller pieces; load non-essential scripts after interaction.
- Avoid heavy work when users tap common elements such as menus and filters.
For CLS
- Set width and height (or aspect ratio) for images, videos and embeds.
- Reserve space for banners and dynamic content.
- Load fonts in a way that does not reflow text dramatically.
See image optimisation and website speed optimisation.
How much it matters for ranking
Page experience is one of many signals; relevance and quality of content matter far more. Core Web Vitals will not lift a weak page to the top, but between similar pages, and for visitors' behaviour, they make a difference. The effect on conversions is often more noticeable than the effect on rankings.
Business decisions behind the numbers
Many Core Web Vitals problems come from business decisions: a large autoplay video on the home page, five tracking tools, a heavy chat widget, a page builder theme. Improving them sometimes means choosing which tools are really needed.
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FAQ
Frequently asked questions
Our PageSpeed score is low but the site feels fast. Who is right?
The lab score simulates a slow phone on a slow network. Check field data from real users in Search Console or PageSpeed Insights; that is what Google uses for evaluation.
Do we need perfect scores?
No. Aim for "good" thresholds on your key templates, especially on mobile. Beyond that, other improvements usually matter more.
How long until improvements show in Search Console?
Field data is collected over a rolling 28-day period, so improvements appear gradually over several weeks.