The amount of members in a group changes the dynamics. Too small and it may not be sustainable. Too large and it can be noisy and problematic. Some communities can flourish on their own, but great communities often emerge from hard work. Getting the right amount of members is a big factor. ### Working group (4-9) A group that works on a specific project should be small enough for direct communication but diverse enough for creative problem solving. Groups around 4-9 members seems like the sweet spot. 7 is a good average. ### Worst size (9-25) Around 9-25 members, probably most strongly between 12-15, group dynamics are the worst. 13 is in the middle and more easily remembered as it is the Judas number. At this size: - Individuals more often feel that they do not get a fair share of time in group conversations - Multiple leaders may struggle for status - Subgroups will often form in unwanted ways ### Non-exclusive Dunbar number (25-75) This is the 'ideal' group size, for a group that is not exclusive, meaning that participants can also be involved in other groups outside of it. Video game clans or guilds seem to converge around 25-75 members. ### Dunbar's number (150) According to Dunbar's research, 147 is the total number of personal relationships that a person rarely goes beyond due to cognitive and time constraints.[^3] This is based on comparing the human neocortex size to other primates and using regression to estimate an ideal group size for humans. [^1][^2] [^1]: Life With Alacrity. 2009. “Community by the Numbers, Part One: Group Thresholds.” September 14. [https://www.lifewithalacrity.com/article/group-threshold/](https://www.lifewithalacrity.com/article/group-threshold/). [[CommunityNumbersPart2009|Annotations]] [^2]: Interconnected, a Blog by Matt Webb. n.d. “Dunbar’s Number and How Speaking Is 2.8x Better than Picking Fleas.” Accessed November 25, 2025. [https://interconnected.org/home/2022/04/05/dunbar](https://interconnected.org/home/2022/04/05/dunbar). [[DunbarsNumberHow|Annotations]] [^3]: Dodds, Peter. n.d. _Co-Evolution of Neocortex Size, Group Size and Language in Humans_. [[doddsCoevolutionNeocortexSize|Annotations]]