How an ad session is defined in AdSense
An ad session is a period of interaction with your site from a unique visitor on a particular device. You can think of the ad sessions metrics as a way of bundling up the ads-related actions a user takes on your site. For example, a single ad session can contain multiple page views and ad impressions.
How long does an ad session last?
By default, an ad session ends after either 30 minutes of inactivity or at midnight United States Pacific Time (PST):
- 30 minutes of inactivity
AdSense starts counting from that moment a user (say, Alice) arrives on your site. If 30 minutes pass without any kind of interaction with the ads on your site from Alice, the ad session ends. However, every time Alice interacts with your site (for example, opens a new page with ads), AdSense resets the expiration time by adding 30 minutes from the time of that interaction.
Let's say Alice arrives on your site at 11:50 PM on August 14 and leaves at 12:10 AM on August 15. AdSense records two ad sessions: one ending at 11:59:59 PM on August 14, and one beginning at 12:00 AM on August 15.
As soon as one ad session ends, the user can start a new ad session. The user can interact with your site during multiple ad sessions occurring on the same day or over several days, weeks, or months.
Differences between sessions in AdSense and Google Analytics
The main difference between ad sessions in AdSense and those in Google Analytics is the way they're measured. AdSense only measures sessions on pages containing ads, whereas Google Analytics measures sessions on all pages, whether or not they have ads. For example, if a visitor to your site doesn't see any ads during their visit (for example, because they're using an ad blocker), AdSense won't record a session, but Google Analytics will record one.
Additionally, you might see differences between sessions in AdSense and Google Analytics in these cases:
- Your pages with AdSense ads might not also have the Google Analytics tracking code on them, and vice versa.
- AdSense might not be able to measure 100% of the sessions on your site, for example, if a user has changed their cookie settings or installed an ad blocker.
- Google Analytics opens a new session every time a user's campaign source changes.
- Google Analytics allows you to change the session timeout so that sessions end after a specified amount of time rather than the default 30 minutes of inactivity.
- Google Analytics might use midnight in a different timezone than AdSense to end sessions.
- AdSense session metrics show how users interact with the ads on your site, whereas Google Analytics shows interactions with your pages. So multiple ad impressions in AdSense might correspond to a single “impression” in Google Analytics.