Team Size

Decades of research and practice indicate that size is one of the most straightforward variables with a strong impact on team performance, but still organizations don’t take it too seriously. Specially those organizations that have a Tayloristic or individualistic approach to getting things done.

Size matters, size really matters.

It depends on the type of task or project, but essentially any group of people bigger than 12 cannot be considered a team anymore. Different authors vary in the numbers but most would agree than between 4 and 9 members is typically an optimal size.

If you cannot have such small teams you should think about what is going on in your organization that won’t allow you to make smaller teams. Perhaps too much specialization, functional division, too many levels of management, lack of trust, too much control, individual performance appraisal, individual rewards, …

Again, we look at the bigger system as responsible for team performance. If you cannot make a team between 4 and 9 people, your organization is highly inefficient, and you cannot expect your teams to achieve high performance.

When creating teams make sure their task is compelling and they have a clear purpose. So, if your solution is to divide a big team by creating smaller functional teams, then you are not improving anything, rather aggravating things. The tendency is to create self-organized cross-functional teams that can deliver value to customer and have the authority to take decisions and manage their processes rather than relying on a management layer or other teams.

Richard Hackman, in his book “Leading Teams” says the following:

Although managers sometimes form teams that are too small to accomplish their work well, the far more common and dangerous mistake is over-staffing them.

Psychologist Ivan Steiner reached the conclusions shown in the next figure.


The actual productivity of a group is its potential productivity minus the process losses. When group size becomes very large, the problems generated far outweigh the incremental resources brought by the additional members.

Several studies remind us that most of the time smaller is really better. Indeed, a team may function better when it has slightly fewer members than the task actually requires.

Group size depends on the size of the task, but a rule of thumb is that a team cannot have more than six members.

There are several theories and studies about the optimal size of a team. For example, Hackman says that the optimal size is 6.2 members, in the world of Agile Software Development it is stated that the appropriate size is 7 ± 2 members.

In the study (Wheelan, Group Size, Group Development, and Group Productivity, 2009) investigated the impact of small and large work groups on developmental processes and group productivity in face-to-face work groups in organizations. The research concludes that groups of 3 to 8 members were significantly more productive and more advanced than groups with 9 or more members. Groups containing 3 to 6 members were significantly more productive and more advanced than groups with between 7 and 11 or more members. Finally, groups with 3 or 4 members were significantly more productive and more advanced than groups with 5 to 6 members.

Susan Wheelan discoveries indicate that as the size increases, cohesion and intimacy descend. The members of larger teams perceived their groups as more competitive, less unified and more argumentative. As you increase the size of the equipment, member satisfaction decreased.

Many studies also show that as group size increases, the amount of communication initiated by members decreases.

Other studies show how as the group size increases, the natural tendency of human beings leads team members to form sub-teams or subgroups that can decisively impact performance.

We also know that the number of communication channels in a team is N * (N-1) where N is the number of members, so the greater the number the harder it will be for team communication to flow correctly.

In other studies, members reported that as size increased members experienced more feelings of threat and inhibition. More disagreements and dissatisfaction with the group were found in larger teams compared to small teams.

This brief review suggests considerable consensus regarding the influence of group size in these processes. Privacy and cohesion, member satisfaction, participation, and expressed disagreement are all affected by larger size teams.

Susan Wheelan study clearly suggests that the size of the working group is associated with the development of the group and its productivity.

Managers and leaders should be encouraged to limit the size of the working groups to the minimum number of members necessary to achieve the objectives.

If your endeavor requires a huge group a people you must think about ways in which you can divide it in small cross-functional teams with a clear and compelling  and well-defined task.

Tools, Techniques & Ideas

  • Managing Flow Efficiency over Managing Resource Efficiency (Lean)
  • Cross-functional teams made of T-Shaped people (Agile)
  • The Bus Factor
  • Divide the task/project by value/purpose not by functional specialization whenever possible
  • “Feed them two pizzas” – A team should be able to be fed by to pizzas
  • Social Loafing – The typical performance loss of big teams

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