It goes without saying that Amazon is one of the most successful companies in history. One of the keys to its success is that they keep their meetings small.

“We try to create teams that are no larger than can be fed by two pizzas. We call that the two-pizza team rule.” – Jeff Bezos

The two-pizza rule makes sense. Too many attendees kill meeting effectiveness.

Consulting firm Bain & Company says that the size of a meeting should be kept to seven or fewer and that each person beyond seven who attends the meeting reduces decision effectiveness by around 10%. Thus, meetings with 17 or more attendees usually can’t make any decisions. Makes sense. And I would think that two medium pizzas is about the right amount for seven people.

But not all meetings are for decision-making.  Another rule of thumb highlighted by Harvard Business Review is the so-called 8 – 18 – 1800 rule:

• If you want to make a decision or solve a problem, keep the number of people in the meeting to less than eight (which is consistent with the two-pizza rule).
• For brainstorming, go as high as 18 people.
• If you want to provide updates or communicate information, go as high as 1,800 people (or higher).