Friend Exchange Rates

I wonder what the exchange rate is on Dunbar’s number.

Popularized by Tipping Point, Dunbar’s number suggests that there’s a limit to social cognition. Roughly speaking, 150 people can form a tight social group; any larger and closeness suffers. Inasmuch, we sacrifice intimacy and trade familiarity for breadth. Is there an optimal social mix?

I’m not critiquing Dunbar’s accuracy or claiming we cap our friendships at 150 people. (My 800 Facebook “friends” might think ill of me for saying so.) But, I inherently feel a physical limit to my intimate capacity: it’s impossibly difficult to know — to really know — a certain number of people. 

To achieve such feats in friendship, I trade intimacy for connectivity. There are ten people I have always been close with (family included), and another twenty or so that are close friends. Call it thirty.

Using 150 as a benchmark, this leaves 120 slots. Using my 800 Facebook-friends as an indicator of my extended network, this means that 800 fit into those 120 intimate slots. Very roughly speaking, I trade one close friend for 6.67 acquaintances.

By comparison, consider someone like Gary Vaynerchuk or Robert Scoble. Assume each has thirty close friends. Both hit the 5,000-friend limit on Facebook. That’s at least 42 acquaintances per close friend slot. That’s a lot of people. Both are connected to thousands more.

I wonder at what point, between the 800 I have and the 5,000 (and more) they have, can they not keep track of, let alone remember, those acquaintances.

What if I were to try to know — to really know — those 800 people I’m connected with. How far could I get?

Or would I just lose intimacy with everyone?

Is that what we’re doing to ourselves?


More: The Dunbar Number as a Limit to Group Sizes

Sloane Berrent
Sloane Berrent

Thanks for sending me this blog post. I was in a conversation with a friend tonight who also works in social media and she was saying at some conferences now she has a conversation with someone - even a really good conversation - and just plain can only remember half of it that next day, or forgets the name of the person she was talking to but remembers the conversation. And drinking was not involved! It's more about how much our brains can handle.

At this past SXSW, the people I remember most and are looking forward to getting to know better are the people I LAUGHED with. Yes good conversation was often weaved through, but it was the people I connected with that seem to have broken through and I remember now. But it's still hard when I get all kinds of Facebook friend requests without comments and I honestly can't remember if I met half of those people before.

I know social media has forever changed our ratio of people we know - but the number we keep close, I agree, is fundamentally the same as it always was. It's a smaller group of those we hold dear. But what happens to these large networks - I'm curious about the next stage of social media and what happens when the information and sheer amount of people we're connected to grows too large to be able to handle. What then?


Mike, I question the value of Dunbar's number, first you need to keep in mind that it varies. It's probably higher for more intelligent people. You seem to be viewing it as something that you can't increase. But isn't that exactly why we use facebook? To keep in touch with more people than we could otherwise? To put our memories about our friends in a digital form so we don't have to remember everything about them? I don't see this as a tradeoff, I'm not giving up intimate friends for more casual ones.

Michael Gruen
Michael Gruen


I'm not explicitly examining intimacy in social media; rather, I'm using the numbers in my social media networks to explore this point: what's the limit to our social cognition?

As for the 35,000 people, I'm sure they expect you to know that they know you, but not the other way around. You are part of that community, for sure; but, how well do you understand that community on an atomic level? You can't know every one of those 35,000 people... so what's the limit? Dunbar shows it's somewhere in the 150-person range. Social media probably enables you to know more, perhaps 300 or 500; regardless, there's a limit.

I'm more interested in thinking about the tradeoff: knowing more people versus really knowing fewer people.

I'm not interested in interviewing 6.67 people for one of my "coveted spots", but rather, I understand that my knowing 6.67 people occupies the energy that I would otherwise give to one, more intimate relationship.

So, what's the limit? Can you know 10 people in exchange for one intimate relationship? 20? 50? 100? I don't know.

Additionally, what's the effect? In our pursuit to know more people (enabled by social media or otherwise), does knowing more people implicitly dilute our intimate relationships? Corollary: does that change our benchmark for "intimate"?

We only have so much social capacity. What's the best way to use it?

As far as I know, there's no social media phenomena to award BFF badges or official interviews for coveted "who's in your Top 5?" spaces on your mobile. (Though, that might be a fun thing to try!)


Hey Michael. I'm confused. Why are we examining intimacy in social media? We who are involved in the community aren't looking to use social media as solely a place to keep up with our close friends. It's a workplace. At my last workplace, I'd guess more than 5,000 people (from a total of about 35,000 worldwide) knew who I was and what I did; I had a high profile job. What's the difference here? Close friends in and out of work (like close friends online & offline) know who they are and know how to catch up with me. Am I missing some phenomena in which social media contacts expect more from me? Am I supposed to send them BFF badges for their blog or something? Your division of numbers give me the image of you interviewing 6.67 people to fill 1 of the coveted spots in your inner circle. I have a small inner circle of online folks myself, so that would be quite a bit of interviews with my 700+ peeps on Twitter. Please treat me as an inner circler and 'splain. Thanks.