Core Web Vitals

Core Web Vitals are a specific, officially named set of three metrics that Google uses to quantify page speed and overall page experience: Largest Contentful Paint, Interaction to Next Paint, and Cumulative Layout Shift, each representing a different dimension of how a real visitor experiences a webpage.

Google announced Core Web Vitals on May 28, 2020, after studying how page performance affected user engagement across millions of pages and concluding the web lacked a standardised, measurable definition of a genuinely good page experience.

The metrics were folded into Google’s ranking algorithm through the Page Experience update, rolling out for mobile search from mid-June through the end of August 2021; the desktop rollout followed between February and March 2022.

Since then, the metrics have continued to evolve: the original responsiveness metric, First Input Delay, was replaced by the more comprehensive Interaction to Next Paint in March 2024, since the older metric only captured a visitor’s very first interaction rather than ongoing responsiveness throughout a session.

Google evaluates Core Web Vitals using two distinct types of data. Field data, drawn from the Chrome User Experience Report (CrUX), comes from real visitors browsing real pages under genuine, varied conditions, and is the data source that actually affects search rankings.

Lab data comes from simulated tests run under controlled, consistent conditions, useful for diagnosing issues during development but not used for ranking purposes, since it doesn’t reflect what visitors with slower devices or connections actually experience. A page must reach the “good” threshold across all three metrics, evaluated at the 75th percentile of its field data, to be considered as offering a good overall page experience.

Example

A developer working on a new product page runs it through a testing tool during development and sees strong lab data results, suggesting the page loads quickly under ideal conditions. After publishing the page, the developer checks Google Search Console a few weeks later and finds that real visitor field data tells a different story: many mobile users on slower connections are experiencing a Largest Contentful Paint well above the “good” threshold, prompting the team to further optimise image sizes specifically for mobile network conditions.

Key characteristics

• Three specific, named metrics: Largest Contentful Paint (loading), Interaction to Next Paint (responsiveness), and Cumulative Layout Shift (visual stability) make up the complete set, each with its own defined “good” threshold.
• Field data determines rankings: Only data collected from real visitors through the Chrome User Experience Report affects search rankings; simulated lab data is a diagnostic tool rather than a ranking input.
• Evaluated at the 75th percentile: A page is classified as having a good score on a given metric only if at least 75 percent of its real visits meet that metric’s “good” threshold.
• Part of a broader set of signals: Core Web Vitals sit alongside other page experience factors Google considers, including mobile-friendliness, HTTPS security, and the absence of intrusive pop-ups.
• Continually refined over time: Google has updated how individual metrics are calculated and measured since their introduction, including replacing First Input Delay with Interaction to Next Paint in 2024.

Related terms

• Page speed – the broader concept of how quickly a page loads and becomes usable, which Core Web Vitals provide a standardised, measurable way to quantify.
• Hosting – the server-based service whose response time is a major factor in a page’s Largest Contentful Paint score.
• Mobile-responsive – a design approach closely tied to Core Web Vitals performance, since mobile scores generally carry significant weight given how much search traffic comes from mobile devices.
• CMS – the underlying content management system, where theme and plugin choices can significantly influence a site’s Core Web Vitals scores.
• Ecommerce – the broader category of online commercial activity in which Core Web Vitals performance has a documented link to conversion rates.

Frequently asked questions

When did Google introduce Core Web Vitals?

Google announced Core Web Vitals on May 28, 2020, then incorporated them into search rankings through the Page Experience update, rolling out for mobile search between mid-June and late August 2021, with the desktop rollout following in early 2022.

What is the difference between field data and lab data?

Field data comes from real visitors browsing pages under genuine, varied conditions, collected through the Chrome User Experience Report, and is the data source that actually affects search rankings. Lab data comes from simulated tests run under fixed, controlled conditions, useful for diagnosing issues during development but not used directly for ranking purposes.

Do I need to pass all three Core Web Vitals to rank well?

Passing all three metrics at the “good” threshold contributes to a positive page experience signal, but Core Web Vitals are only one of many ranking factors Google considers. A page can still rank well with imperfect Core Web Vitals if its content and other SEO factors are strong, though performance acts as a meaningful tiebreaker between otherwise similar pages.

Why did Interaction to Next Paint replace First Input Delay?

First Input Delay only measured the delay before a visitor’s very first interaction with a page, missing how responsive the page remained throughout the rest of the session. Interaction to Next Paint, which officially replaced it in March 2024, captures responsiveness across all interactions during a visit, giving a more complete picture of real-world usability.

AliDropship: An all-in-one platform for starting dropshipping in 2026

AliDropship is a dropshipping platform that covers store creation, product imports, order automation, and marketing within a single system. It is designed for users with no prior ecommerce experience, though it also supports scaling for more established stores.

🛍️ Free turnkey store

New users receive a free pre-built store – set up, designed, and stocked with products. The store includes a ready-to-use product catalogue and a standard storefront design. It also comes with hosting, a domain, SSL, and payment systems already set up and included.

📦 Products

The platform provides access to a product catalogue covering both trending and niche items, with one-click import to your store. The catalogue is updated regularly to reflect current market availability. Products can be browsed, filtered, and added without leaving the platform.

🚚 Shipping & fulfillment

AliDropship provides access to a vast catalogue of products from global suppliers and handles order fulfillment automatically once a purchase is made. Customers receive tracking information directly, and orders are processed without manual intervention from the store owner.

📣 Marketing & promotion tools

The platform includes built-in marketing tools covering email campaigns, discount management, SEO settings, and social media integration. These are available within the dashboard and do not require third-party subscriptions for basic use.

👌 Ease of use

AliDropship requires no coding knowledge. The dashboard contains all the necessary tools for managing your store, products, and orders in one place. Additional features and products can be added as the store grows without rebuilding the existing setup.