I’ve been running mastermind groups since 1995, and I’ve seen groups of all sizes. There are some questions you need to ask yourself before deciding how many members should be in your mastermind group:
Meetings need to have a begin and end time, and many meetings that run over 90 minutes can run out of steam without frequent breaks. Yet breaks also cause interruption of the energy levels. So first decide how long each meeting will be, then go on to Question 2.
Members need time to first verbalize their situation before masterminding can begin in earnest. Some members are quick and can sum it up in five minutes or less. Others need 10-15 minutes just to set the stage. THEN you need time to mastermind after that. We did an experiment in one of my mastermind group meetings recently: we had a non-timed meeting, just to see what would naturally occur. Thirty minutes per member was our average time for each hot seat.
Remember that your meeting typically includes some sort of opening and closing, as well as possible guest speakers, training or other events. Allow time for those in your agenda, then plan accordingly.
In my mastermind groups, I tend to look for 4-6 members per group. Less than four and the energy level can drop (though I know several very successful mastermind groups with three members in them!), and more than six members will probably cause you to run out of time. However, if you’re doing half-day or full-day meetings, you may be able to include more members.