 Kevin K. Lee [X](https://twitter.com/kevinkiklee) [GitHub](https://github.com/kevinkiklee)
Published: September 15, 2026
[Chrome User Experience Report (CrUX)](https://developer.chrome.com/docs/crux) ad metrics are an [experimental](https://developer.chrome.com/docs/crux/methodology/metrics#experimental-metrics) set of ad-related measurements provided by the browser. Ad metrics provide transparent telemetry to help advertisers and sites value ad opportunities and make product decisions. This data is aggregated publicly so anyone can track, optimize, and compare the ad experience of sites.
CrUX ad metrics measure the values in a 28-day rolling window average to capture how real users are experiencing the site across different devices and network conditions. The metrics measured from real users are called *field data*. We also provide tooling to measure these on the developer's local device (lab data) to provide immediate feedback for local development and debugging.
CrUX ad metrics are gathered by Chrome from the following platforms that meet the user eligibility [criteria](https://developer.chrome.com/docs/crux/methodology#user-eligibility):
- **Supported platforms:** Chrome on Windows, macOS, Android, ChromeOS, and Linux.
- **Excluded platforms:** Chrome on iOS, Android WebView embedded applications, and other Chromium-based browsers.
CrUX data is collected from real browsers around the world, based on certain browser options which determine user eligibility. A set of dimensions and metrics are collected which determine how users experience their sites.
> [!IMPORTANT]
>
> ## Relationship to Core Web Vitals
>
> Though Core Web Vitals and CrUX ad metrics share the same CrUX pipeline, the ad metrics are not part of the Core Web Vitals initiative. Additionally, CrUX ad metrics are not scored like Core Web Vitals are, lacking categories such as "Good," "Needs improvement," or "Poor".
## The metrics
Ad experience is quantified by four metrics that measure different dimensions of how ads affect the browsing experience:
| Category | Description |
|---|---|
| [Ad Count](https://developer.chrome.com/docs/ads/metrics/count) | Counts the visible ads on a page, measuring the average number of distinct ad frames visible in the viewport as the user scrolls. |
| [Ad Density](https://developer.chrome.com/docs/ads/metrics/density) | Measures the visual footprint of ads within the viewport throughout a session as the user scrolls, defined as the average fraction of the visible [viewport](https://developer.mozilla.org/docs/Web/CSS/Guides/CSSOM_view/Viewport_concepts) area occupied by ad frames. |
| [Ad Weight: CPU](https://developer.chrome.com/docs/ads/metrics/weight-cpu) | Measures the cumulative computational load caused by loading and running ad scripts and assets. |
| [Ad Weight: Network](https://developer.chrome.com/docs/ads/metrics/weight-network) | Measures the cumulative network traffic load caused by loading and running ad scripts and assets. |
## Accessing CrUX ad metrics
The CrUX ad metrics are available in [CrUX Vis](https://cruxvis.withgoogle.com/#/?view=ads&url=https%3A%2F%2Fwww.example.com), the [CrUX API](https://developer.chrome.com/docs/crux/api), [CrUX History API](https://developer.chrome.com/docs/crux/history-api), and the [DevTools Ad panel](https://developer.chrome.com/docs/ads/detection#devtools_support). To learn more about using these tools, see the [CrUX ad metrics tooling guide](https://developer.chrome.com/docs/ads/tooling).
We are working on adding the ad metrics to the [CrUX dataset on BigQuery](https://developers.google.com/web/tools/chrome-user-experience-report/bigquery) to enable users to query and analyze the ad metrics using SQL.
## Ad detection
For CrUX ad metrics, Chrome uses its ad detection logic to identify which parts of a page are ads.
For a detailed breakdown of how the ad detection engine works, read the [ad detection developer guide](https://developer.chrome.com/docs/ads/detection).
## Feedback
If you have any questions or feedback regarding ad metrics, reach out to us at the [Chrome UX Report Google Group](https://groups.google.com/a/chromium.org/g/chrome-ux-report).