Core Web Vitals

What are Core Web Vitals?

Core Web Vitals are three performance metrics from Google that measure how fast a page loads, how quickly it responds to clicks, and how stable the layout is while loading. Google introduced them in 2020 and made them a search ranking factor in June 2021.^[1]

A page passes the Core Web Vitals test when 75% or more of real-world visits score "Good" on all three metrics.

What are the three Core Web Vitals metrics?

Largest Contentful Paint (LCP) measures loading speed. It tracks when the biggest visible element (usually a hero image or heading) finishes rendering.

• Good: 2.5 seconds or less
• Needs improvement: 2.5 to 4.0 seconds
• Poor: over 4.0 seconds

Interaction to Next Paint (INP) measures responsiveness. It replaced First Input Delay (FID) in March 2024. INP watches every click, tap, and keyboard action during a visit. It reports the slowest (or near-slowest) response time.^[2]

• Good: 200 milliseconds or less
• Needs improvement: 200 to 500 milliseconds
• Poor: over 500 milliseconds

Cumulative Layout Shift (CLS) measures visual stability. It tracks how much the page layout jumps around after it starts loading. Common causes include images without set dimensions, ads that push content down, and fonts that swap after the initial render.

• Good: 0.1 or less
• Needs improvement: 0.1 to 0.25
• Poor: over 0.25

Why do Core Web Vitals matter?

Search rankings. Google uses Core Web Vitals as a ranking signal. Pages that pass all three metrics get a small but real advantage in competitive search results.^[1]

Bounce rate and revenue. Slower loading times push visitors away. Google's research shows that a one-second delay in LCP can cause measurable drops in conversion rates, especially for e-commerce sites.^[3]

User experience. Poor LCP makes pages feel slow. High CLS causes accidental clicks when content jumps. Poor INP makes buttons feel unresponsive. For a government services portal or an insurance claims page, these problems frustrate users and increase support calls.

Compliance and accessibility. Slow, unstable pages create barriers for users on older devices or slower connections. This disproportionately affects people in rural areas and those using assistive technology. Content teams and accessibility leads should track Core Web Vitals as part of their quality standards.

How do you measure Core Web Vitals?

Google Search Console shows field data from real Chrome users for all pages with enough traffic. This is the best source for IT teams monitoring site-wide performance.

PageSpeed Insights gives both field data and lab data for individual URLs. Content teams can use it to check specific pages before and after updates.

Lighthouse (in Chrome DevTools or as a command-line tool) provides lab data with detailed fix recommendations. Developers use this during builds.

The web-vitals JavaScript library enables real-user measurement within your own analytics setup. This is useful for organizations that want Core Web Vitals data in their existing dashboards.

How do large organizations improve Core Web Vitals?

For sites with thousands of pages, improvements often focus on:

• Compressing and properly sizing images to speed up LCP.
• Setting width and height on all images and ads to prevent CLS.
• Reducing JavaScript execution time to improve INP.
• Using a content delivery network (CDN) to reduce load times globally.

IT teams typically own these optimizations. But content teams play a role too. Uploading oversized images or embedding heavy third-party widgets can undo technical improvements.

How Askem Helps

For large organizations managing hundreds of pages, tracking page performance alongside traffic metrics in a single dashboard helps non-technical team members spot slow pages. Analytics platforms like Askem combine performance data with page views and engagement metrics, so content owners can flag loading issues to IT without running separate Lighthouse audits. Category-based filtering lets each team focus on their own section of the site.

Sources

1. Google Search Central — Understanding Core Web Vitals and Google Search: https://developers.google.com/search/docs/appearance/core-web-vitals
2. Google — Interaction to Next Paint (INP): https://web.dev/articles/inp
3. Google — The business impact of Core Web Vitals: https://web.dev/articles/vitals-business-impact