An ad session is a period of interaction with your website 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 that a user takes on your website. For example, a single ad session can contain multiple page views and ad impressions.
AdSense uses cookies to associate an ad session with a unique user and device. In some cases, it’s not possible to associate an ad request with an ad session, for example, if a user or user’s browser setting has disabled or deleted cookies, or they’ve opted out of personalised ads.
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 the moment that a user (say, Alice) arrives on your website. If 30 minutes pass without any kind of interaction with the ads on your site from Alice, then the ad session ends. However, every time that Alice interacts with your site (for example, opens a new page with ads), AdSense resets the expiry time by adding 30 minutes from the time of that interaction.
- Midnight
Let's say that Alice arrives on your website at 11.50 p.m. on 14 August and leaves at 12.10 a.m. on 15 August. AdSense records two ad sessions: one ending at 11:59:59 PM on August 14, and one starting at 12:00 AM on August 15.
As soon as one ad session has ended, the user can start a new ad session. The user can interact with your website during multiple ad sessions occurring on the same day or over several days, weeks or months.
Differences between ad sessions in AdSense and Google Analytics
The main difference between ad sessions in AdSense and those in Google Analytics is the way in which they're measured. AdSense only measures ad sessions on pages containing ads, whereas Google Analytics measures ad sessions on all pages, whether or not they have ads. For example, if a visitor to your site can't see any ads during their visit (for example, because they're using an ad blocker), AdSense won't record an ad session, but Google Analytics will record one.
Additionally, you might see differences between ad 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 ad sessions on your website, for example, if a user has changed their cookie settings or installed an ad blocker.
- Google Analytics opens a new ad session every time that a user's campaign source changes.
- Google Analytics allows you to change the ad session timeout so that ad 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 ad sessions.
- AdSense session metrics show how users interact with the ads on your website, whereas Google Analytics shows interactions with your pages. So multiple ad impressions in AdSense might correspond to a single 'impression' in Google Analytics.
