What is Core Web Vitals?

Definition

Core Web Vitals are Google's set of page experience metrics that measure how a real user perceives a page loading. The three current metrics are:

• LCP (Largest Contentful Paint) — how long the largest visible element takes to render. Good: under 2.5 seconds.
• INP (Interaction to Next Paint) — how quickly the page responds to user interaction. Good: under 200 milliseconds. INP replaced FID (First Input Delay) in March 2024.
• CLS (Cumulative Layout Shift) — how much the page layout shifts unexpectedly during load. Good: under 0.1.

Google measures Core Web Vitals through the Chrome User Experience Report (CrUX), which aggregates real-user metrics from Chrome users. Sites that pass all three metrics for 75 percent of their users on both mobile and desktop are considered to have good Core Web Vitals.

Why It Matters

Google confirmed Core Web Vitals as direct ranking signals in the 2021 Page Experience update. While Core Web Vitals are not the largest weight in the ranking algorithm — content relevance and links still dominate — they are a real tiebreaker between similar pages and become more important on mobile-first indexing where every millisecond of page speed materially affects user experience.

The business case is often stronger than the SEO case. Google's own research suggests a meaningful portion of mobile users abandon sites that take too long to load. Better Core Web Vitals reduce bounce, increase conversion, and lift revenue independently of ranking impact — the SEO benefit is a bonus.

How It Works

Google offers two types of Core Web Vitals data:

• Field data. Real-user metrics collected from Chrome users via the CrUX report. This is what Google uses for ranking. Available in Google Search Console and PageSpeed Insights (for pages with sufficient traffic).
• Lab data. Synthetic tests run under controlled conditions (Lighthouse, WebPageTest). Useful for debugging specific issues but not what Google uses for ranking.

Optimizing Core Web Vitals typically involves reducing render-blocking resources, optimizing images, preloading LCP elements, deferring non-critical JavaScript, and reserving space for elements that load asynchronously (to prevent layout shifts).

SEObolt's Page Speed feature tracks LCP, INP, and CLS with historical trends for both desktop and mobile so you can catch regressions after deploys.

Related

• Schema markup — a technical SEO signal alongside Core Web Vitals
• Page Speed (SEObolt feature) — tracks LCP, INP, and CLS over time
• Site Health (SEObolt feature) — broader technical SEO monitoring
• SEObolt for Ecommerce — where CWV impact on conversion is largest

Frequently Asked Questions

What is the difference between INP and FID?

INP (Interaction to Next Paint) replaced FID (First Input Delay) as a Core Web Vital in March 2024. FID measured only the delay before the browser could start processing the first interaction. INP measures the full latency from any interaction through the visual response, giving a more complete picture of interactivity across the whole session.

Is Core Web Vitals a direct Google ranking factor?

Yes, since the 2021 Page Experience update. The impact is not as large as content relevance or link authority, but Core Web Vitals do function as a tiebreaker between otherwise similar pages, and mobile pages are especially affected.

How do I check my Core Web Vitals?

Google Search Console has a Core Web Vitals report showing field data for your site. PageSpeed Insights gives per-page field data alongside a lab-data Lighthouse audit. Chrome DevTools' Performance panel is useful for debugging specific issues. SEObolt's Page Speed feature tracks the metrics over time so you can spot regressions.