I first learned about the two-pizza rule a few years ago and have always wanted to get around to writing down my thoughts on it.  From time to time, there comes around a simple fun concept that solves a seemingly tricky problem to solve.

In a nutshell, the two-pizza rule is about team size and the rule is that team meetings and size should be small enough, two pizzas could feed them. (obviously, there is a side note here about the size of the pizza, how many slices we all entitled too ).

Size Matters

Jeff Bezos, Amazon is often credited with the phrase two-pizza rule. He wanted to ensure that meetings remained productive and decided meetings should not happen first thing in the morning or be larger than what two pizzas could feed. He also believes that having smaller teams mean the teams themselves are more productive and can output more.  

  • People work better in smaller teams;
  • People feel they have more of a voice in smaller teams;
  • Junior members are mentored more effectively;
  • Skillsets of members are recognised and valued;
  • Change is easy to accommodate and implement in smaller teams.

Simply put, small teams feel more autonomous and have a greater sense of ownership.

The science behind two pizzas

What fascinated me about the two pizza rule, wasn’t the gimmicky name or the fact there was substantial evidence it had worked for Amazon (Amazon Web Services and Amazon e-commerce both grew from small teams). Instead, it was the science that backs up the idea is more interesting.

Having worked in both large and small teams my personal experience is that small teams are happier and achieve more success than large ones.

The two-pizza rule says that no team can be larger than five to seven people.

The reason for this is the more members of the team, the more communication channels are opened up that need maintained.  The formula that determines the number of communications in the team size is :

where n is the number of people in the team—the formula created by J. Richard Hackman, a psychologist and team-dynamics expert.

Using the formula, we can work out how many connections there are to maintain. The following shows how the number of connections required to be maintained as the team size grows.

The best way to explain this is to quote Hackman himself:

“The larger a group, the more process problems members encounter in carrying out their collective work …. Worse, the vulnerability of a group to such difficulties increases sharply as size increases.”

What Hackman is saying here is the more substantial the team size is, the more likely it is to experience communication breakdowns and become more difficult to coordination problems.

Less is more

There was a study also carried out by researchers Staats, Milkman, and  Fox.  The experiment involved two teams in trying and building a lego figure.  Team A had two members, and Team B had four members.  You can probably guess where the story ends, and you would be correct.  Team B, the larger team took 44% longer time to finish the challenge than Team A and yet, their confidence in completing the task quicker was greater.

Wrapping Up

It can be easy to continue to add resources to a problem in an attempt to complete it quicker. Still, considering the research done by team dynamic experts and psychologists, it is clear that smaller teams with more autonomy, less outside interference and being allowed to work a way that works for them is far more effective than a large team.

People feel safer in small teams and therefore more likely to have the confidence to try new things and speak up without fear of being beaten down.

Finally, operating small teams means peoples unique skills are recognised more easily, valued more and likely put to better use.

Anyone for Pizza?