Jeff Bezos said he believed in “two pizza teams”: if a team couldn’t be fed with two pizzas, it was too big. Small teams have less communication challenges and can be more agile as they have autonomy, yet are clearly accountability for their goals.
At Amazon once a two Pizza team (2PT) is approved they are free to execute relatively autonomously to maximize its fitness function—to pursue creative strategies and to set its own internal priorities. There’s no need to coordinate even across teams, let alone across divisions, to get something done. This model has helped Amazon stay nimble and innovative even as it has grown.
More communication isn’t necessarily the solution to communication problems — it’s how it is carried out. Compare the interactions at a small dinner — or pizza — party with a larger gathering like a wedding. As group size grows, you simply can’t have as meaningful of a conversation with every person, which is why people start clumping off into smaller clusters to chat.
For Bezos, small teams make it easier to communicate more effectively rather than more, to stay decentralized and moving fast, and encourage high autonomy and innovation. Here’s the science behind why the two-pizza team rule works.
Communication Gets Terrible as Team Size Grows
The issue with larger teams isn’t quite the team size itself. As organizational psychologist and expert on team dynamics J. Richard Hackman would point out, it’s the number of links between people that is the problem. Take a look at the formula for determining the number of links between members in a group: n(n-1)/2.
As group size increases, the links start to get unwieldy.
- If you take a basic two-pizza team size of, say, 6. That’s 15 links between everyone.
- Double that group for a team of 12. That shoots up to 66 links.
- A small business of 50 people has an incredible 1225 links to manage.
The cost of coordinating, communicating, and relating with each other snowballs to such a degree that it lowers individual and team productivity. Hackman explained, “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.”
Two-Pizza Teams Protect Against the Team Scaling Fallacy
Many managers and leaders fall into the mental trap that adding more people to a team is always good. People are your best assets, so adding more assets to a project should power up progress right?
The fact is, larger team size makes people overconfident. This is the tendency for people “to increasingly underestimate task completion time as team size grows,” as researchers Bradley Staats, Katherine Milkman, and Craig Fox explain. In one of their experiments, they discovered that when tasked to build the same Lego figure, two-person teams took 36 minutes while four-person teams took 52 minutes to finish — over 44% longer.
Yet the larger teams were almost twice as overoptimistic about how long they’d take.
When a project is running behind, you want to get something done faster, or there’s an ambitious milestone at stake, it seems reasonable to add on more people power. Sticking to a max number of a two-pizza team will balance a natural tendency to underestimate the costs and friction of dealing with those extra links.
A 2PT might look like this:
- 1 2PT lead (or 2PTL)
- 1 designer/UX specialist
- 1 or 2 UI developers
- 1 or 2 server-side developers
- 1 QA specialist
- 1 product owner/business analyst
This is a very general list, but this is the general idea of small and agile DevOps teams. DevOps is a cultural change that encourages, rewards and exposes people taking responsibility for what they do, and what is expected from them.
Traditional IT is far more segmented into silos (as presented by Adrian Cockroft at DockerCon):
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