What Are Google Core Web Vitals?

Google Core Web Vitals are a set of metrics developed by Google to measure the real-world user experience on web pages. High scores on Core Web Vitals can help to ensure a good user experience and improve rankings on Google’s search engine results pages.

Core Web Vitals include:

• Largest Contentful Paint (LCP): This is the time it takes for the largest content element to become fully rendered in the portion of the web page the viewer sees. This metric helps development teams understand how users perceive the page load speed. A good LCP score is considered to be 2.5 seconds or faster.
• Cumulative Layout Shift (CLS): This measures the amount of unexpected shifting and changing in the page layout that a viewer experiences. This is a measure of visual stability. A good CLS score is less than 0.1.
• Interaction to Next Paint (INP): This measures latency of all clicks, taps, and keyboard interactions with the page throughout its lifespan and reports the single metric which all interactions are under. It’s a measure of responsiveness and indicates when a page is consistently able to respond quickly to most users. INP replaced First Input Delay (FID) in March 2024.

Understanding and optimizing these metrics can help development teams build more responsive and engaging web pages and websites.

In the digital world, the quality of user interactions with websites is closely connected with business success. Users and customers expect websites to load quickly, be visually pleasing, be easy to navigate, and to offer seamless functionality and interactivity. When websites load too slowly and perform poorly, users are likely to go elsewhere to get information or buy products. As a result, poorly performing sites degrade user satisfaction, damage brand perception, and negatively impact the bottom line.

Monitoring and optimizing for Google Core Web Vitals performance metrics helps site owners deliver the best possible user experiences. Additionally, because search engines like Google factor Core Web Vitals data into rankings, optimizing for these metrics can help increase organic search and broaden the customer base.

Making enhancements based on Google Core Web Vitals inevitably leads to better page experiences for end users.

• Pages load faster. Users are likely to engage more with pages that load faster.
• Pages are more responsive. This translates to smoother and more satisfying user experiences, as users experience less waiting for sites to react.
• Pages are visually stable. Optimizing for Cumulative Layout Shift prevents page elements in a page from moving around as a page loads, making a more comfortable browsing experience.
• Sites are more mobile friendly. Core Web Vitals are especially important for pages viewed on mobile devices — a rapidly growing percentage of all web page views.

Optimizing for Google Core Web Vitals can improve a page’s rankings in search engine results pages (SERPs) for several reasons.

They are a direct ranking factor. Google explicitly states that it relies on Core Web Vitals when ranking pages in its SERPs. That’s due in part because websites that load faster and provide better user experiences are more likely to keep users engaged.

They provide better experiences. Positive experiences reduce bounce rates and signal to search engines that a website has higher quality and greater relevance.

They have higher conversion rates. Sites optimized on Core Web Vitals tend to have higher conversion rates, a metric that search engines incorporate when determining SEO rankings.

They’re better for search engine crawlers. Optimizing for Core Web Vitals enables faster loading times and more efficient site architecture. This helps search engine crawlers to index more pages faster, potentially increasing visibility in search results.

Google Core Web Vitals can be measured with a variety of website monitoring tools, including real user monitoring (RUM) and synthetic testing solutions.

RUM

RUM tools capture and analyze every user interaction with a website, collecting data from real user behavior in actual browsing conditions. This provides an accurate picture of how users experience a website in the real world, across a variety of geographies, network conditions, and devices.

Synthetic testing

Synthetic testing uses scripts that simulate user behavior in controlled environments to establish baseline performance and identify any potential issues with Core Web Vitals before they impact real users. By making changes and repeating tests over time, development teams can optimize performance in preproduction.

Google’s tools for measuring and tracking Core Web Vitals include:

• Chrome User Experience Report (CrUX): This solution delivers real-world, user-experience data on Core Web Vitals metrics. CrUX data is collected from Google Chrome users who have opted in to reporting on their browsing history and usage statistics.
• PageSpeed Insights: This tool analyzes the content of a web page, then uses data from the CrUX to identify areas that need improvement and generate suggestions to make the page faster.
• RUM tools: Various real user monitoring tools, such as Akamai mPulse, will collect and show aggregated Core Web Vitals metrics for all users of a website.
• Google Search Console's Core Web Vitals report: This report offers a comprehensive view of a site’s performance, based on real-world usage data or field data.
• Lighthouse and Chrome DevTools: These offerings provide lab data to help developers diagnose issues and improve user experiences on their websites. Lighthouse provides a score for each Core Web Vital, while Chrome DevTools offers more in-depth analysis.

Improving Core Web Vitals often requires a holistic approach to web development and design.

• Optimize Largest Contentful Paint (LCP): Improve loading speed by optimizing server response times (Time to First Byte), utilizing a content delivery network (CDN), optimizing images and video formats, and removing any unnecessary third-party scripts. Techniques such as lazy loading of images and other resources can significantly reduce LCP times by loading only the necessary content as the user scrolls through the page.
• Improve Interaction to Next Paint (INP): Try to reduce any input delay by ensuring there are no long tasks on the main JavaScript thread. Web workers can be used to offload long tasks onto background threads that won’t affect browser rendering. Additionally, minimize any processing and simplify layout so that website response is immediate to user interactions.
• Improve Cumulative Layout Shift (CLS): Ensure visual stability by adding size attributes to image and video elements (or CSS aspect ratio boxes). Avoid inserting content above existing content, and minimize animations that cause layout shifts.

For mobile users, ensuring a website is optimized for smaller screens and slower network connections is critical, as these factors can dramatically affect Core Web Vitals scores.