What is actually the ideal size for a team?

[Oct 2025] Generally speaking, teams are groups of individuals that shall complete specific tasks in a timely manner. These tasks may be one-off or recurring in nature. Accordingly, teams may be temporary or permanent. There are often no guidelines regarding their exact size. Does this mean that size is irrelevant when it comes to teams?

The formation, modification, or removal of teams is usually discussed publicly when organizations are undergoing massive change processes. In Germany, for example, the replacement of the CEO of Deutsche Bahn was recently accompanied by the announcement that the executive board would be reduced in size at the same time. Last month Lufthansa Group announced that it would cut 4,000 administrative jobs as part of its ongoing digitalization efforts. And just a few days ago, automotive supplier Bosch surprised everyone with the news that a further 13,000 jobs would be cut in the short term, not only in administration but also in development, sales, and production. In all cases, existing teams are also affected. And in all these cases the significance of these plans for the respective teams remains unclear for the time being.

Against this backdrop, it is worth discussing some fundamental aspects of determining the size of successful teams. Teams are usually exposed to a variety of information or stimuli. This includes knowledge of and interaction with key parameters of the task. The type of communication within the team, the handling of unexpected events (new circumstances, emotions, disruptions, etc.), and the type of decision-making within the team result in further stimuli, especially if these things are not discussed sufficiently at the very start. Last but not least, team members regularly report that they perceive the short processing time as a significant limitation and source of demotivation.

From this selection of demands to team members, it becomes clear that in complex transformation processes “as small as possible” is too unspecific as a guideline for an ideal team size. It can be helpful to view the work of teams as an intangible exchange process that should generate as much interaction as possible between members: contributions from one person generate responses from others, resulting in further contributions from the one person or other members. According to Social Exchange Theory (Thibaut, Kelley), team members evaluate all such responses in terms of the benefits they can derive from them or the associated costs. Subsequently, solution options can then be derived from the structured weighing of benefits and costs.

In order to achieve a great variety of ideas, there is therefore a strong case for appointing many people as “idea generators” for a team. In a second step, the question should be asked whether the number of team members determined in this way still allows for reasonable control of the actual task. This includes, in particular, the ability of the team leader to recognize conflicts between team members and to manage them in a way that is satisfactory for all involved. Medium-sized teams have an advantage in this respect.

The experience of coopartner is that leading medium-sized teams, i.e. 5 to 10 people, is already very demanding for a single person. Teams larger than this require significantly more time for the preparation and follow-up of team’s work, as well as for relationship management, especially if a lively exchange of ideas shall be cultivated within the team