How is CCU Calculated?


I have a question about how CCU is calculated: Players who join a session are definitely will be counted against CCU but I am not sure about the players who are not part of a session yet? For example, are players who are just looking for a match and only querying the available sessions, considered as part of CCU? I am thinking about showing the number of active session in the main page of my game and I want to know if it will cost me or not.