source on Google
Core Web Vitals are three measurements Google uses to describe how a page feels to a visitor. They cover loading, visual stability and responsiveness. This guide explains each one in plain language, the usual causes of a poor score and a simple order of work to fix them.
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The three Core Web Vitals in plain language
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Largest Contentful Paint (LCP) measures how long the main content takes to appear. Cumulative Layout Shift (CLS) measures how much content moves while the page loads. Interaction to Next Paint (INP) measures how quickly the page responds after a tap, click or key press.
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Google explains the thresholds and the reasoning in its web.dev guide to Web Vitals. Our short definitions are in the glossary, starting with the LCP entry.
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Why LCP is often slow
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LCP is usually the hero image or a large heading. A slow score normally comes from a slow server response, an oversized image, render-blocking CSS or JavaScript, or a font that delays text.
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Start with the image. Serve it at the size it is shown, use a modern format such as WebP and avoid lazy-loading the hero, since that delays the element visitors need first.
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How to reduce layout shift
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You have probably seen a button jump just as you tap it. That is layout shift. The usual cause is an image, ad or banner that loads without reserved space, so the content below it moves.
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Set width and height on images and video. Reserve space for embeds and banners, and avoid inserting content above what the visitor is reading.
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How to improve responsiveness
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A high INP usually means the browser is busy running JavaScript. Theme scripts, page builders, chat widgets and tracking tags are common causes. Remove any script you do not use, load non-essential scripts after the page is ready, and test on a mid-range phone.
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Where to check your Core Web Vitals
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- Google Search Console groups your pages by Core Web Vitals status.
- PageSpeed Insights gives a score and a list of fixes for one page.
- Chrome DevTools shows exactly which element causes a shift or a slow response.
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Field data from real visitors matters more than a single lab test. Use lab results to find causes, then confirm the improvement in Search Console.
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Common causes on WordPress and Shopify sites
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- Too many plugins or app scripts loaded on every page
- Full-size hero and product photos uploaded from a camera
- Slow hosting with no caching in place
- Page builders that add large amounts of CSS and JavaScript
- Chat, review and tracking widgets loaded before the main content
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A simple order of work for Core Web Vitals
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- Check Search Console to see which page groups fail.
- Fix image sizes and reserve space for images and embeds.
- Remove unused plugins and app scripts.
- Check server response time and add caching where pages are built on every request.
- Retest, then move to the next group of pages.
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Next steps
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Our speed optimisation service starts from $200 and includes a before and after report. For a quick first check, the WordPress speed checker is free to use.
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Test on real devices and slow connections
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Lab tools run on fast computers, so they can hide problems that real visitors face. Test your main pages on a mid-range phone over a slower mobile connection. Watch for the moment content jumps, and for buttons that feel slow to respond.
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When a fix improves the lab score but not the phone experience, trust the phone. Real visitors matter more than a perfect test result.
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Mistakes to avoid when fixing Core Web Vitals
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- Lazy-loading the hero image, which delays the main content
- Removing a script that a form or checkout still needs
- Adding a caching plugin without testing that pages still update
- Chasing a perfect score on a page visitors rarely open
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Focus on the pages that earn enquiries and sales first. Those pages deliver the most value when they feel fast and stable.
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Frequently asked questions
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What are the three Core Web Vitals?
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The three Core Web Vitals are Largest Contentful Paint (LCP) for loading, Cumulative Layout Shift (CLS) for visual stability, and Interaction to Next Paint (INP) for responsiveness.
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Where can I check my Core Web Vitals scores?
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Google Search Console groups pages by Core Web Vitals status, and PageSpeed Insights gives a score and fixes for one page at a time. Use field data from Search Console to confirm real visitor experience.
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Can a speed plugin fix Core Web Vitals on its own?
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Sometimes it helps, but the biggest gains usually come from smaller images, fewer scripts and reserved space for content. A plugin works best alongside those fixes, not instead of them.
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Ready to plan your next step?
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If you want a clear plan for your site, our team can review your current setup and suggest the next steps. Request a free proposal and we reply within 24 hours.