 Kevin K. Lee [X](https://twitter.com/kevinkiklee) [GitHub](https://github.com/kevinkiklee)
Published: September 15, 2026
> [!WARNING]
> **Experimental:** Ad metrics are [experimental metrics](https://developer.chrome.com/docs/crux/methodology/metrics#experimental-metrics), and they may evolve based on user feedback.
The Ad Weight: Network metric describes the network resource consumption by ads, which may impact page performance.
## How Chrome calculates Ad Weight: Network
Ad Weight: Network is measured throughout the life of the page visit. The total compressed wire bytes transferred to load all ad-related resources---such as scripts, images, and stylesheets---are computed as:
$$ \\text{Network Weight} = \\text{sum}\\left(\\text{bytes of ad resources}\\right) $$ Ad Weight: Network calculation
Ad Weight: Network is reported in kilobytes as an integer rounded to the nearest kilobyte.
The [Chrome User Experience Report (CrUX)](https://developer.chrome.com/docs/crux) aggregates data across all eligible Chrome users, and provides a 75th percentile number across those page views. Only pages with ads are considered for the CrUX ad metrics. Pages and origins [without at least one authorized seller defined in `ads.txt` file](https://developer.chrome.com/docs/ads/methodology#reporting_scope) won't have ad metrics data in CrUX. This data is available at the URL and origin-level, subject to the [CrUX eligibility criteria](https://developer.chrome.com/docs/crux/methodology).
## Collecting Ad Density through JavaScript
There are challenges reporting across cross-origin iframes which most ads are delivered through. Therefore, there is no JavaScript API to allow similar detection for Real User Monitoring (RUM) tooling.
## Tooling
Ad Weight: Network is 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.
## 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).