Average session duration is: total duration of all sessions (in seconds) / number of sessions.
Individual session duration is calculated differently depending on whether there are engagement hits on the last page of a session.
An engagement hit is one that results from an event that does not have the opt_noninteraction parameter applied. For example, if you set up event tracking to track events like playing videos, then each video play results in an engagement hit. If you apply the opt_noninteraction parameter to an event, then it no longer results in an engagement hit. Learn more
No engagement hits
If there are no engagement hits on the last page, then the duration is calculated as follows:
The time of the first hit on the last page - the first hit on the first page
For example:
- Page 1: first hit: 10:00 AM
- Page 2: first hit: 10:05 AM
- Page 3: first hit: 10:10 AM
- 10:10 minus 10:00 = a session duration of 10 minutes (600 seconds)
Engagement hits
If there are engagement hits on the last page, then the duration is calculated as follows:
The time of the last engagement hit on the last page - the first hit on the first page
For example:
- Page 1: first hit: 10:00 AM
- Page 2: first hit: 10:05 AM
- Page 3: first hit 10:10 AM; last engagement hit: 10:15 AM>
- 10:15 minus 10:00 = a session duration of 15 minutes (900 seconds).
Metric calculation
To calculate average session duration, Analytics sums the duration of each session during the date range you specify and divides that sum by the total number of sessions. For example:
- Total Session Duration: 1000 minutes (60,000 seconds)
- Total Sessions: 100
- Average Session Duration: 1000/100 = 10 minutes (600 seconds)