The question of how large a team can be often comes up in the context of team building. Of course, a team can be any size but there comes a point at which the size of the team and the number of relationships in it starts to work against the effectiveness of the group.

Dunbar's number, calculated by Professor Robin Dunbar of the University of Oxford, is an estimate of the number of relationships that our minds are capable of handling simultaneously. According to Professor Dunbar, this number has remained at around 150 throughout human history, from the tiny village communities in which our ancestors spent their whole lives up to the modern age of international travel and social media.

The reason for this limitation on our number of friendships may be the size of our brains. Professor Dunbar suggests that the volume of the region known as the neocortex could be the limiting factor restricting the number of relationships we are able to maintain. In order to maintain a personal relationship with someone, we have to be able to remember details about their lives and their relationships with us and other people in the group. Our brains can only handle this much information for a certain number of people, which seems to be about 150.

Dunbar's estimate of 150 relationships is reflected in many different contexts. It is the approximate size of many village communities, and of the remaining hunter-gatherer societies still existing in remote parts of the world. It also matches studies of the average number of Christmas cards that people send out each year, and the average number of friends that people have on social networking sites.

Relationships Need Familiarity

Within the group of about 150 friends, there will be different levels of familiarity. We might have just a few very intimate friends, perhaps 15 people to whom we feel close, and 50 to whom we speak regularly. We can also have relationships that exist beyond the group of 150, so that we can feel a connection to people who work for the same company, or who share our allegiances to a sports team or nation, without having personal relationships.

Dunbar's number is just an estimate based on averages, so it is possible to find individuals who have far fewer friendships, or who can manage many more. However, if people try to manage more than 150 relationships, they will begin to struggle and feel less connected to the people in that group. The more people we try to fit into our community, the more the quality of these relationships will deteriorate. However many names you might have in your address book, there are probably no more than 150 people with whom you have personal, stable, and trusting relationships.

W.L.Gore & Associates, the manufacturers of Gore-Tex actually run their business on this principle. When a division expands beyond 150 employees then they actually split it up into two smaller divisions. This may seem extreme, however the company believes that it makes communication better and helps them to manage an efficient business.

The average size of a team on our team building events seems to be around 30 people and at this size there is no doubt that relationships can be very strong. At this size people are able to understand how they get on with each of their team mates but also, importantly, how others in the team get on with each other.

Other Team Building Theories

Follow the links in the text to look at some of the other team building ideas that we cover on our website.

Belbin is one of the more widely used team building programmes based on work styles and putting the right type of people together in a team.

MBTI is another personality based team development theory which is about individual personalities rather than working styles.

Tuckman's Forming, Storming, Norming, Performing covers the stages that teams go through from their conception through to working together effectively. 

Have a look at all of the team building theories that we cover on this site.