Core Web Vitals
Also known as: CWV, Page Experience Metrics
Core Web Vitals are Google's set of user-experience metrics measuring loading, interactivity, and visual stability: Largest Contentful Paint, Interaction to Next Paint, and Cumulative Layout Shift. They are measured from real-user field data and used as part of the page experience signals.
Key Takeaways
- Core Web Vitals are three Google metrics: Largest Contentful Paint, Interaction to Next Paint, and Cumulative Layout Shift.
- They measure loading speed, interactivity, and visual stability from real-user field data, not just lab tests.
- Google uses Core Web Vitals as part of its page experience ranking signals.
- Field data comes from the Chrome User Experience Report, reflecting how real visitors experience your pages.
- Passing all three thresholds together, not just one, is what counts as a good page experience.
How It Works
Core Web Vitals combine three field measurements taken from real Chrome users visiting your site. Largest Contentful Paint tracks how long the biggest visible element takes to render, Interaction to Next Paint tracks responsiveness to taps and clicks, and Cumulative Layout Shift measures how much content jumps around during load.
Google collects these numbers through the Chrome User Experience Report and rolls them into its page experience signals. Because the data is drawn from actual devices and connections, a page can look fast in a lab tool yet still fail in the field. Assessment happens per URL, then aggregates to page groups when a single URL lacks enough traffic.
Core Web Vitals do not work in isolation. They sit alongside signals like Structured Data, which helps engines understand your content, and Index Coverage, which determines whether pages are eligible to rank at all. Improving Largest Contentful Paint often delivers the fastest, most visible win.
Why It Matters
They are a confirmed ranking factor and, more importantly, correlate with real user satisfaction. Poor scores raise bounce and abandonment, so improving them can lift both rankings and conversion at the same time.
Example
A local dentist notices patients bouncing on mobile. Lab tests show green scores, but Chrome field data reveals a slow Largest Contentful Paint because a large unoptimized hero image loads late on cellular connections. After compressing the image and preloading it, the field score moves into the good range, and appointment-request form completions climb over the next few weeks.
Common Mistake
Optimizing only lab scores in tools like Lighthouse while ignoring field data from the Chrome User Experience Report. Rankings use real-user data, so a green lab score on fast hardware can hide slow experiences for actual visitors.
Frequently Asked Questions
What are the three Core Web Vitals?
Largest Contentful Paint (loading), Interaction to Next Paint (interactivity), and Cumulative Layout Shift (visual stability). INP replaced First Input Delay in 2024 as the responsiveness metric.
Are Core Web Vitals a ranking factor?
Yes. Google confirms they are part of its page experience signals. They are one input among many, so strong vitals help but rarely outrank highly relevant content on their own.
Why do lab scores differ from field scores?
Lab tools test on a controlled device and network, while field data reflects real visitors on varied hardware and connections. Rankings use field data, so always check the Chrome User Experience Report.
Where do I measure Core Web Vitals?
Google Search Console shows field data grouped by status, PageSpeed Insights shows both lab and field results, and the Chrome User Experience Report provides the underlying real-user dataset.