Monthly Tracked Users are the total number of users that Segment tracks within a given month. Think of it like MAUs, but including anonymous visitors as well as logged in users. Any user who takes an action that is tracked by Segment will count as a Tracked User, regardless of how many individual events Segment tracks for that particular user.
How does it work?
At the end of a month, we look at all the events that have passed through Segment. For any event with a user_id, we see if we’ve already seen that user_id this month, and if not we count it as a “User”. For any event without a user_id, we see if we’ve already seen its anonymous_id this month, and if not we count it as a “Visitor”. We add your Users and Visitors together, and use that as your MTU count for the following month (so your bill on March 1st is based on your MTU count in February).
How do I estimate my MTUs?
Add together your current MAU number and the number of unique visitors you have to your publicly accessible sites. That’s it!