Ad Count

Kevin K. Lee

Published: September 15, 2026

Experimental: Ad metrics are experimental metrics, and they may evolve based on user feedback.

The Ad Count metric describes how many ads a most users are seeing at once on the site.

How Chrome calculates Ad Count

Ad Count is measured with viewport sampling during the life of the page visit. As a user scrolls through the page, Chrome takes the average number of ads in the viewport throughout the page visit, and reports that number when the user navigates away from the page.

The final metric is represented as the average count of distinct elements (for example, frames or images) visible in the viewport throughout the session:

$$ \text{Ad Count} = \text{Average}\left(\text{count of distinct elements visible in viewport}\right) $$

Ad Count calculation

Ads are counted once per second. Ad Count is reported as a number with 2 points of decimal precision—for example, 2.00. This is formatted as a string in the CrUX API.

As an example, if:

• A page loads with 2 ads showing in the viewport and the user reads that for 5 seconds
• The user then scrolls down and no ads show in the viewport and the user reads that for 5 seconds

Then reported Ad Count for that session for that page will be 1.00 which is calculated with:

$$ \frac{(2\text{ ads} \times 5\text{ sec}) + (0\text{ ads} \times 5\text{ sec})}{10\text{ sec}} = 1.00 $$

Ad Count example calculation

The Chrome User Experience Report (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 won't have ad metrics data in CrUX. This data is available at the URL and origin-level, subject to the CrUX eligibility criteria.

Collecting Ad Count 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 Count is available in the CrUX API, CrUX History API, and the DevTools Ad panel. To learn more about using these tools, see the CrUX ad metrics tooling guide.

We are working on adding the ad metrics to the CrUX dataset on 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.