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What’s the ideal team size?

This question is often neglected when putting together a team, but numbers can significantly affect team performance.

Jeff Bezos, founder of Amazon, famously came up with the ‘two-pizza’ rule: the idea that every team should be small enough that it could be fed with two pizzas.

Optimal team size depends, to some extent, on team goals and function, but Meredith Belbin’s research gives us some important steers when it comes to team size.

Firstly, perhaps it’s important to define a team.

  • Team: Meredith Belbin defines a team as a limited number of people selected to work together for a shared objective in a way that allows each person to make a distinctive contribution.
  • Group: By contrast, a group is a number of people who are brought together for a common purpose, but who are too numerous for Team Role relationships to form.

Groups and teams behave differently

The bigger the group, the greater the pressures towards conformity. And the stronger the group structure, the less opportunity there is for people to express disagreement.

On the other hand, if groups are unstructured, group members become anonymous. In a professional context, this is likely to mean that we don’t reap the full benefits of individual strengths.

  • The Ringelmann effect explains the inverse relationship between group size and individual contribution to completion of a task.

In other words, as numbers in the group increase, members of that group become less productive. Groups lose motivation (called social loafing) and coordination. Each person puts in significantly less effort than they would do if working alone, believing that others will pick up the slack. The group becomes increasingly inefficient as a result.

  • Forsyth (2006) demonstrated that social loafing could be countered (and individual performance boosted) by setting clear and challenging goals, and by identifying individuals’ strengths so that each person perceives themselves as indispensable to the group’s performance.

However, the larger the group, the more difficult it becomes to identify and separate out strengths in a meaningful way. And even if the group possesses the abilities and expertise required for a given task, they may not be able to co-ordinate their efforts effectively.


During his decade-long research at Henley Management College, Dr Meredith Belbin experimented with syndicates of ten or eleven members – a number which he hoped would allow for diversity without reducing group identity.

The syndicates took part in the Executive Management Exercise (EME), a high-intensity, interactive management game which displayed a number of management skills. Performance depended not only on the internal performance of each syndicate, but on the performance of others.

Dr Belbin discovered that a group of this size was found to reach its limits during round-table discussions designed to thrash out plans and policies with a view to making decisions. It became difficult to give each person enough ‘airtime’ in discussions without prolonging the decision-making process unduly or reducing efficiency.

Medium-sized teams

Dr Belbin began experimenting by making teams smaller.

Even with larger teams of eight, they found that a number of teams in the EME tended to be dominated by two, three or four members.

One or two others would be working at the peripheries and the remainder would be disengaged and dissatisfied.

In short, teams of eight fall somewhere between an ideal command group and a smaller, more intimate team setting, and aren't able to derive the benefits of either setup.

Smaller teams

When the researchers reduced the number to six, the team became more stable. (Teams of seven pitted against teams of six were unable to make the most of their numerical ‘advantage’.)

But if there are nine Team Roles, why was this the case?

Well, larger numbers necessitated structure – a suitable chairperson and each person playing one defined Team Role. This is a difficult set of criteria for real teams to fulfil.

By contrast, a team of six could cover a broad range of technical skills and Team Roles with each person ‘doubling up’ on roles, so that, with the right composition, it was well balanced.


Since most of us have more than one Team Role strength that can be played to good effect, this is more realistic and attainable for real teams.

It is not without significance that, for a period of at least a decade, six endured as the number that was found, on the internal evidence at Henley, to be most suitable for enabling a management team to tackle a complex problem.

Teams of four

If smaller is better, how do teams of four fare in comparison to teams of six?

Meredith Belbin’s research used another game, Teamopoly, a variation on Monopoly whereby property could change hands only as a result of auction, tender or negotiation.

The researchers increased the pressure on each team by limiting them to four members instead of six.


The result of having teams of four

  • Relationships

The four-person teams were less well-equipped to tackle complex problems, but the teams achieved a degree of intimacy, involvement and engagement that the six-person teams couldn’t match.

As Meredith commented, “If they got on well, they were harmonious and positive on all fronts; but where relationships did not work out, the cross-currents seemed immensely complicated.”

  • Strategy

In performance terms, every winning company made at least one major strategic mistake, compared to the six-person teams taking part in the EME. It was easier to achieve balance with six-person teams.

  • Leadership

Having six in a team necessitated a chairperson (and a certain level of formality). On the other hand, four people often turned into a leaderless group, which became unstable at moments of crisis. As such, it was more dependent on Team Role complementarity for success.

In a four-person team where rotated leadership was understood and practised effectively, these negative effects might have been turned to a positive.

Don’t make teams too small

In teams of four or more, the team has a ‘life of its own’. Membership may change without threatening the team’s integrity or structure.

However, in a three-person team, this is not the case. Personalities have a greater impact upon decision-making. The team is more vulnerable, because even small changes may affect its cohesion.

Team size: a ‘compromise between conflicting forces’

As Meredith Belbin writes in Management Teams: Why They Succeed or Fail, the ideal size of a team ‘is a matter of compromise between conflicting forces’.

  • We need enough team members to ensure diversity of behaviour (Team Role balance), knowledge, experience and ability.
  • Numbers can become inflated in an effort to ensure that all relevant individuals or departments are adequately represented.
  • However, for an effective team, it is important to ‘reduce noise’ and maximise involvement by keeping teams small.

In summary...

"The ideal size of a team is a matter of compromise between conflicting forces.

On the one hand there is a need to widen the composition, bringing in the full range of knowledge, experience and ability.

The wishes of individuals or representatives to participate through consultation or the political desirability of securing commitment of all departments are amongst the many pressures that operate to inflate numbers.

Yet on the other hand there is the need to reduce noise and maximize involvement and individual effectiveness by keeping the team small."

  • Meredith Belbin | Management Teams


Meredith Belbin Partner Belbin

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