The 4 Magic Group Sizes

Choosing the right size for meaningful experiences

For every gathering, there is a corresponding ideal size.

Size alone won’t make a great experience, but it can either elevate the experience or stand in the way of unleashing it’s full potential.

It turns out that there are rough size clusters that have specific impact on how a group behaves. Different hosts and facilitators have their own lists but it roughly comes down to this:

4-6; 12-15; 30; 150

The group sizes can be placed on a continuum between intimacy and energy.

Smaller is better for trust, decision making, progress and learning. Bigger is better for energy, movement and momentum.

Let’s move into each of the magic group sizes to find out what they’re best for.

Groups of 4-6

There’s special magic around this rough size.

Groups between 4 and 6 work great in terms of intimacy, high levels of sharing. People are more likely to challenge, share opinions and engage in constructive dissent and arrive at appropriate solutions.

Groups of four have been identified as the sweet spot for the number of people who can easily engage in conversation. People naturally cluster in groups of four.

Groups of five have often been found to be a very effective team size to make decisions and move forward together. Also study groups inside the altMBA programme have a size of five.

Groups of six allow you to rearrange people as pairs, triplets, or a full half-dozen. It's absolutely great for a training group in order to maintain energy.

Research shows that groups with seven or more members are more susceptible to confirmation bias.

Groups of 12-15

The next interesting number is around 12. It’s roughly the point to which groups can come together in a facilitated conversation without experiencing cognitive overload.

Gatherings at this size bring a certain mystery and constructive unfamiliarity. It’s small enough to build trust and intimacy and large enough to offer diversity of opinion.

There’s one dinner format which is called 15 Toasts. The dinners give 15 guests the opportunity to engage in an open conversation around an important topic with deep reflection and meaningful exchange.

Groups of 30 and 150

Thirty starts to feel like a party. It comes with a certain layer of mystery, buzz, energy, and possibility.

A good portion later the next interesting number is 150. Intimacy and trust is still palpable at the level of the whole group. It’s the right size before the group becomes an audience.

The anthropologist Robin Dunbar also found that it’s the number of stable social relationships that humans can maintain. The natural size of a tribe.

Moving along the continuum of intimacy and energy

In my favourite experiences we actually changed group sizes during the actual event. Last year I visited an online conference where we would see the whole crowd at the beginning but then got assigned into smaller intimate workshops to dive into specific topics.

The same can be done in a course or training environment with intimate study groups. The altMBA has 120 people sorted into cohorts of 20 and people get assigned into study groups of 5. And they still have plenty of chances to meet everyone in the program.

Wether we are designing for learning, inspiration or connection. We can always use the magic sizes to spice things up.

Thanks for reading along and have a lovely Sunday!