How three (or four) is the magic number for (online) breakout groups

Like many other facilitators, I’ve been running meetings online for the last twelve months. In particular I’ve been looking to ensure people are able to participate in a way that’s productive and enjoyable. I have to say I’ve learnt a lot. From people I’ve worked with, from trying things out and by accident, of course.

One of the things I’ve settled on is that online, unfacilitated breakout groups, work best with threes (or the occasional fours if threes don’t quite fit the size of the group). My online activities tend to be designed around this number.

I’m a big fan of Liberating Structures and it’s been fun seeing which of these participation techniques might be adapted to online meetings. Along with Matt Clack, I’ve been facilitating something called ScrutinyMeetup for local government officers and one of the things we learnt early on is that putting people into pairs (which a lot of liberating structures rely on) doesn’t really work. There are perhaps a couple of reasons for this. The first is that one on one interactions, particularly with strangers, seem to be more anxiety inducing for some people on Zoom, for example, than they might be if we were meeting face to face, using a big space and inviting people into pairs. The second reason is to do with the technology. Sometimes, online, people take a while to move from the main room to a breakout room. This can leave someone on their own, wondering what to do, asking for help etc.

So ok, if the minimum is three, how come the maximum is four?

Well, there is science to explain this. Dunbar et al, found, using data from various settings, that everyday conversations rarely exceed four people [1]. It’s something that’s pretty noticeable to be honest. Informal groups, meeting socially, just tend to split into groups of three or four people. This might be to do with various things. The physical spaces associated with a ‘circle’ of five and over lead to gaps of more than 2 metres between people that might be uncomfortable for friendly talk. It might be that most people don’t have the cognitive capacity to work with groups of more than four [2]. Either way, the idea that people ‘naturally’ work best in groups of no more than four, is supported by good evidence.

In breakout rooms, where there is no facilitator guiding the conversation, it’s important to create an environment where people can find it easy to work together. So ‘no more than four’ makes a good rule.

As well as supporting a ‘naturally comfortable’ way of working, threes (and fours) can enhance participation. A paper by Waller et al,[3] (summarised here) takes this idea and applies it to 12 person juries. They show that dividing the group into fours encourages ‘greater equality of contribution’ and leads to participants experiencing less ‘less inhibition from participation due to the activities of others’. There is an obvious maths to this, of course. The time anyone gets to contribute relates to both the length of the group and the size of the group. A six minute group for three people allows around two minutes of contribution each (and it’s a much easier shared task to help ensure that everyone gets a fair turn). Increase the size to six people and the average becomes one minute each with a greater chance that some will not contribute at all. You can increase the time, of course, but that means limiting the number of activities or having overlong meetings.

Online platforms such as Zoom can handle large numbers of people and, if groups are unfacilitated, it’s as easy to set up 20 groups of three as 10 groups of six if you are happy for them to be random. So, given what we know about having ‘no more than four’. Why wouldn’t you aim for groups of three?

By the way, If you think I might be able to help with online facilitation, please do let me know via my contacts page.



[1] Dunbar, R.I., Duncan, N.D. and Nettle, D., 1995. Size and structure of freely forming conversational groups. Human nature, 6(1), pp.67-78.
[2] Krems, J.A., Dunbar, R.I. and Neuberg, S.L., 2016. Something to talk about: are conversation sizes constrained by mental modeling abilities?. Evolution and Human Behavior, 37(6), pp.423-428.
[3] Waller, B.M., Hope, L., Burrowes, N. and Morrison, E.R., 2011. Twelve (not so) angry men: managing conversational group size increases perceived contribution by decision makers. Group Processes & Intergroup Relations, 14(6), pp.835-843.


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