If you had to guess, how many people would you estimate you could reasonably call friends? Of course, this will vary person to person and also depends on how we define “friend”. Think about it, take a guess, and read on to see how close you came to *Dunbar’s Number*.

From the Wikipedia article on Dunbar’s number:

Dunbar’s number is a suggested cognitive limit to the number of people with whom one can maintain stable social relationshipsâ€”relationships in which an individual knows who each person is and how each person relates to every other person. This number was first proposed in the 1990s by British anthropologist Robin Dunbar, who found a correlation between primate brain size and average social group size. By using the average human brain size and extrapolating from the results of primates, he proposed that humans can comfortably maintain 150 stable relationships.

Here’s how Dunbar defined a friend: someone you would not feel embarrassed about joining uninvited for a drink if you happened to bump into them in a bar.

The specific number has been challenged, but it seems reasonable to assume there exists a limit on the size of one’s meaningful, real-world social network. This consideration leads to some interesting applications. For example, the outerwear company Gore-Tex learned, by trial and error, that 150 employees is the optimal workgroup and limited their building sizes accordingly.

In 2018, Dunbar further hypothesized that we invest about two-thirds of our social time on roughly 15 people. An interesting exercise is to see how that number fits with the size of your own personal inner circle.

Read more about Dunbar’s Number
here and, for a deep dive, check out Dunbar’s 2010 book *How Many Friends Does One Person Need?*.