What Are Core Web Vitals and Why They Matter for User Experience
Core Web Vitals are a set of performance metrics that Google uses to assess the quality of user experience on a web page. They form part of Google’s page experience signals and directly influence how your site appears in search results.
How Core Web Vitals work: LCP, INP, and CLS
These three metrics help evaluate how usable and responsive your page feels to visitors. Each addresses a distinct aspect of the user journey:
- LCP (Largest Contentful Paint) — measures loading performance. Good: ≤ 2.5 seconds.
- INP (Interaction to Next Paint) — measures responsiveness to clicks, taps, or key presses. Target: ≤ 200 milliseconds.
- CLS (Cumulative Layout Shift) — measures visual stability. Good: ≤ 0.1.
A Lighthouse score of ≥ 90 is considered “good” and aligns with Google’s thresholds.
However, poor Core Web Vitals can significantly reduce your click-through rate, harm rankings, and increase bounce rates — even if your content is excellent.
Why this matters for you
These metrics are not just technical numbers — they reflect how users feel while navigating your site.
They reveal moments of frustration — for example, when a button doesn’t respond or text “jumps” under the user’s finger.
This is especially critical for charitable, educational, or mission-driven projects, where trust and usability are foundational to engagement.
Therefore, improving Core Web Vitals isn’t just a technical task — it’s an investment in your audience’s experience.
Real-world application
In our technical SEO audit, we measure Core Web Vitals using Lighthouse.
We then provide actionable recommendations: image optimisation (WebP/AVIF), deferred JavaScript loading, and fixed element dimensions to prevent layout shifts.
How to measure Core Web Vitals
You can check your metrics using free tools: Lighthouse (in Chrome DevTools), PageSpeed Insights, or Google Search Console.
For example, PageSpeed Insights identifies exactly which elements delay loading or cause layout instability.
Tools for developers
To collect field data automatically, use the web-vitals JavaScript library. It measures LCP, INP, and CLS from real user sessions — not just lab simulations.
This gives you accurate insights into how your audience actually experiences your site.
Official resources
Author: seoadmin • Updated: 2 January 2026