What Are Core Web Vitals? Site Speed and Experience Scores

Three Metrics, One Goal: Good Experience

When Google ranks websites, it considers not only the quality of the content but also the experience of accessing it. Core Web Vitals turn that experience into numbers. As of 2024, the current set consists of three metrics: LCP, INP, and CLS — measured separately on both desktop and mobile.

• LCP (Largest Contentful Paint): Time for the largest image or text block on the page to load. Good threshold: under 2.5 seconds. 2.5–4s is 'needs improvement', above 4s is 'poor'.
• INP (Interaction to Next Paint): How quickly the page responds when a user clicks a button or taps a field. Replaced FID (First Input Delay) in March 2024. Good threshold: under 200 milliseconds.
• CLS (Cumulative Layout Shift): Unexpected movement of buttons, text, or images while the page loads. Good threshold: under 0.1. Users accidentally tap the wrong element — this harms both perception and conversions.

How Do These Scores Affect Rankings?

Google incorporates Core Web Vitals into search rankings as a 'page experience signal'. It's important to understand this correctly: these signals are a ranking factor, but they don't override content quality. Weak content won't reach the first page just because your site is fast. However, when two sites are comparable in content, the one with better Core Web Vitals scores will rank higher. Additionally, a slow site negatively affects your ad Quality Score — which can increase your cost per click.

• Slow LCP cause: large, uncompressed images → switch to WebP, add sizing attributes, use 'preload' for critical images.
• High INP cause: heavy JavaScript → remove unused code, split large JS bundles (code splitting).
• Poor CLS cause: images without dimensions or late-loading ads → add width/height to all image and video tags, reserve space for ad slots in advance.
• To measure everything: the 'Core Web Vitals' report in Google Search Console + PageSpeed Insights (free, instant per-URL analysis).