Frequently Asked Questions
Get answers to the most common questions about Core Web Vitals and our tool
What are Core Web Vitals?
Core Web Vitals are three specific metrics that Google considers essential for a great user experience: LCP (Largest Contentful Paint) measures loading performance, INP (Interaction to Next Paint) measures interactivity, and CLS (Cumulative Layout Shift) measures visual stability. Since 2021, these metrics are official Google ranking factors.
Is this tool free?
Yes, our Core Web Vitals testing tool is completely free to use. There's no registration required, no limits on the number of tests, and no hidden costs. We use the official Google PageSpeed Insights API to provide accurate analysis.
How accurate are the results?
Our results come directly from the Google PageSpeed Insights API, which uses Google's Lighthouse engine. This is the same data that Google uses to evaluate websites. The accuracy is as reliable as Google's own PageSpeed Insights tool.
What's the difference between Mobile and Desktop scores?
Mobile and Desktop scores can differ significantly because they simulate different devices and network conditions. Mobile tests use a throttled connection and simulate a mid-tier mobile device, while Desktop tests simulate a standard desktop computer with a faster connection.
Why is my Mobile score lower than Desktop?
Mobile scores are typically lower because the test simulates a slower network connection and a less powerful device. Additionally, mobile users often encounter more layout shifts due to responsive design changes. Focus on optimizing images, reducing JavaScript, and ensuring your site is truly mobile-friendly.
What's the difference between Field Data and Lab Data?
Field Data comes from real Chrome users visiting your site over the past 28 days (from the Chrome User Experience Report). Lab Data is collected in a controlled simulated environment using Lighthouse. Field Data shows real-world experience, while Lab Data helps identify specific issues to fix.
How often should I test my website?
We recommend testing after any significant changes to your website, such as new features, design updates, or server changes. For ongoing monitoring, testing weekly or monthly is a good practice. Keep in mind that Field Data updates approximately monthly.
Why don't I see Field Data for my site?
Field Data requires sufficient traffic from Chrome users. If your site is new or doesn't receive much traffic, there may not be enough data in the Chrome User Experience Report (CrUX) to display Field Data. Lab Data will still be available.
Are you affiliated with Google?
No, we are not affiliated with or endorsed by Google. We are an independent service that uses the official Google PageSpeed Insights API to provide performance analysis. Google, PageSpeed Insights, and Lighthouse are trademarks of Google LLC.
How can I improve my Core Web Vitals scores?
Common improvements include: optimizing images (using modern formats, compression, lazy loading), minimizing JavaScript (removing unused code, deferring non-critical scripts), reserving space for dynamic content to prevent layout shifts, and using a fast hosting provider or CDN. Check the Opportunities and Diagnostics sections of your report for specific recommendations.
Still have questions?
Check out our documentation for more detailed information.