Core Web Vitals: What They Are and Why They Destroy Rankings
Google's page experience signals are now a confirmed ranking factor. We break down LCP, FID, and CLS in plain English — and how to fix them.
Since Google made Core Web Vitals an official ranking factor, we've seen sites drop significantly in rankings not because of content issues, but because of performance problems that went unnoticed for years.
The three metrics that matter
Largest Contentful Paint (LCP) measures how long it takes for the main content of a page to load. Google considers anything under 2.5 seconds "Good". Common culprits: unoptimised images, slow server response, render-blocking CSS and JavaScript.
Interaction to Next Paint (INP) measures responsiveness — how quickly your page responds when a user interacts with it. It replaced First Input Delay in 2024. Long tasks on the main thread are usually the problem.
Cumulative Layout Shift (CLS) measures visual stability — does your content jump around as it loads? CLS above 0.1 is a problem. Reserve space for images and embeds, avoid injecting content above existing content.
How to measure them
Use Google's PageSpeed Insights, Search Console's Core Web Vitals report, or the Web Vitals Chrome extension for field data. Always fix field data (real user data) over lab data — Google ranks based on what real users experience.
Quick wins
Compress and properly size images (WebP format, explicit width and height attributes). Move render-blocking scripts to the bottom of the body or use defer/async. Use a CDN. Minimise third-party scripts — analytics, chat widgets, and ad platforms are often the biggest culprits.
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