Core Web Vitals are three Google metrics that measure real-world page experience: Largest Contentful Paint (LCP) for loading, Interaction to Next Paint (INP) for responsiveness and Cumulative Layout Shift (CLS) for visual stability. Passing them supports a better experience and is part of Google’s page experience signals.
The three metrics and their good thresholds
- LCP: how long the main content takes to appear. Good is 2.5 seconds or less.
- INP: how quickly the page responds to taps, clicks and key presses. Good is 200 milliseconds or less.
- CLS: how much the layout jumps while loading. Good is 0.1 or less.
Google assesses these at the 75th percentile of real visits, separately for mobile and desktop. INP replaced First Input Delay as a Core Web Vital in March 2024.
How to check your scores
Use Google Search Console’s Core Web Vitals report for real-user data, PageSpeed Insights for both field and lab data, and Lighthouse in Chrome DevTools for testing fixes. Field data from real visitors is what counts for assessment.
How to improve each metric
- LCP: compress and properly size the main image, use fast hosting and caching, and avoid render-blocking scripts.
- INP: reduce heavy JavaScript, remove unused plugins and split long tasks.
- CLS: set width and height on images and embeds, reserve space for ads and banners, and load fonts carefully.
Do Core Web Vitals guarantee rankings?
No. Content relevance and quality matter far more, but a slow or unstable page can lose visitors and hold back otherwise good content.
Frequently asked questions
What replaced First Input Delay?
Interaction to Next Paint (INP) replaced First Input Delay as a Core Web Vital in March 2024.
Why do my lab and field scores differ?
Lab tools test one simulated load. Field data comes from real users on varied devices and networks.
Need help with this?
Our Speed & Core Web Vitals service can handle this for you. Request a quote.