How many people can I connect with, really? (Dunbar + friends?)

If you’ve read any network theory, you’re probably familiar with Dunbar’s Number, or the idea that groups tend to fall off quickly in effectiveness and cohesiveness once they exceed approximately 150. The finding came from some anthropological research originally, and leading companies such as W.L. Gore have used Dunbar’s number as the ceiling for work group sizes and to aid in efficiency and team collaboration. But what about your “personal” Dunbar number? When considering social media, you may have an overlapping group of friends from Facebook, Twitter, Linkedin, Email, and other places — but where’s the operative or active group?  Is the overall number of connections higher than 150, or does Dunbar’s theory still hold?

I believe that Dunbar’s number is still relevant in the context of social media, but that it is a constantly changing set.  Dunbar’s number for social media comprises the ~150 most important people in each overlapping social set with whom you stay in contact. Given that social sets move and reconfigure, it’s reasonable to hypothesize that I might have a set of 150 most important people in Facebook, 150 people whom I read most on Twitter, 150 people with whom I correspond most on email, etc. But as it turns out, the number isn’t 4 x 150 after all: it’s just a lot closer to the 150 people you most care about at the moment, depending upon where and how you spend your time on and offline.   So you can connect with more than 150 people, but it’s hard to believe that you can stay engaged meaningfully with more than 150 people at a time.

A disclaimer: I work at Gist, where I think about how to make users of our service more successful. I’ve noticed when using Gist (and when using other tools) that the number of people I communicate with meaningfully on a regular basis isn’t as high as I thought. Dunbar’s number notwithstanding, I’m a pretty connected person and I thought that between my various connections I was communicating with many more people on a regular basis. It turned out that I am communicating with a lot of Gist users and with my established networks. But the difference I didn’t see as clearly before was that this personal connection (the Personal Dunbar Number, if you will) varied by recency of communication, importance of the person in my overall network, and by the other groups with which I’m communicating.  In any given period of time I don’t communicate with a larger set than 150 or so people, but the time between periods of communications is dropping, and the reach of these communications is increasing.

Because I can learn more about the news published about and by the most important people in my network, and because it’s easy to change that focus depending upon the facet of the network I’m viewing, my “Personal Dunbar Number” is growing and is larger than 150 people.  But there’s a catch — I don’t know if the people on the other end of the network feel the same way — and look forward to finding out the answer to that question in the coming months.  In the meanwhile, I will be trading time for insights and using social media tools like Gist to help me share these insights with the most valuable people in my network.


12 thoughts on “How many people can I connect with, really? (Dunbar + friends?)

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  1. I do believe that my personal dunbar number is likely higher than 150, but probably far smaller than 500, somewhere in the middle perhaps. What I find more interesting, however, is the fact that the people in that community changes over time, it is not always the same 150 (or so).

    This is part of what excites me about social conversations and social tools. As my interest flows from topic to topic the people that I am able to engage with flows with the topic, providing constant opportunities for learning, constant opportunities to meet new people and grow my overall network.

    Great post Greg, you have me thinking…


    1. John –
      Thanks for your feedback. People in your community do change over time. It would be great to have social media tools that would help you track the net adds/drops across multiple networks, not just an individual network.



  2. Greg:

    I’m not sure you need to create the new concept of a “personal Dunbar’s number” to explain the differences you describe in having different circles of connections through, Facebook, Gist, Linked In, Twitter, email, etc.

    Bottom Line:
    For me it sounds like you have one single social network. It may hit about 150 people. And it spans the boundaries of several other distinct networks. Some people in your network are in those other networks. Some are not. You communicate with some people more than than others, sometimes using a universally shared communication channel (email, phone, U.S. Mail) and other times using social media channels and technology that are proprietary to each community (Twitter, FB messages, LI messages.)

    Here’s How I Reach That Bottom Line:
    Academic social network analysis (SNA) may already have a theory that explains what you describe. I’ve been studying this work for a while because I think it provides meaningful and measurable insights that have tremendous applications in the marketing analytic and strategy work I do. Yet, I don’t hold myself out as an expert in social network analysis. At least not yet. 😉

    Anyway, SNA measures social networks with several factors, and one of them may help explain your observations – “in-betweenness.” It measures, to over simplify it, if you sit between one or more other networks, or say circles of friends. People who sit on the edge of different networks can combine and share information across them. This is what is sounds like you describe by segmenting your connections by website or by email. I’ve done the demographic market research, each of the websites you mention has populations with different demographic characteristics – in short they are different circles of friends and you are a “boundary spanner” who connects them within your own social network.

    When you talk about how you connect with some people through more than one of those websites and email, this affects the SNA measure”strength of connection.” The more communication channels you use with one person in the network, the stronger your connection. BTW, this also demonstrates for me the difference between social media channels and social networks. Social media is just a new and additional communication channel.

    Full disclosure: I’m among the people Greg connected with thru his work with Gist.

    1. Bruce –
      This is a fascinating analysis. Is there a readable (in layman’s terms) summary of this SNA work available online? Who are some theorists that I should be reading to learn more about this topic?



  3. Greg –

    Great post. I think it brings up an interesting issue of scale on social media and just connections in general.

    As the space gets bigger, the world gets more connected and interconnected, but relevance for each individual gets trickier.

    I think we are moving towards one stream of everyone we have ever met and connected with (Facebook? I dunno…)

    But you will be able to organize based on relevance.

    As I test Gist out over the next couple of months, it could be an amazing tool for doing just that.

    1. David –
      Thanks for your comment. I agree that determining relevance for contacts in your personal network is a key question for social media tools (and for networking in general, online and offline). The tricky thing is, of course, that a contact may be greatly relevant to you and less relevant to me, and vice-versa.

      I’m looking forward to your feedback.



  4. Interesting post, Greg! This question has come up a number of times for me, as people question how I could truly “follow” 600 people on Twitter, or why I would want to create a list of more than 500 people. Dunbar’s number is about “stable social relationships” in which you “know” each person. I agree with you that in social media the definition doesn’t hold in quite the same way – but I think beyond just the rate of change aspect.

    Take you and me, for instance. Do you and I have a “stable social relationship”? We follow each other on Twitter, you’ve retweeted me a few times, but for instance I didn’t know you worked for Gist until this post. Yet you’re still someone I would consider as being in my social network. In fact in a given week I might interact over Twitter with a few hundred people. Are they “stable social relationships”? Probably not for the most part. But again I would consider them to be part of my social network. Hence my “personal” Dunbar number might still be ~150, but like John Moore said, the number of people we’re interacting with using social tools might reach 200-300.

    So maybe it’s less about a “personal” Dunbar number and more about a “social media” number – in which the relationships are looser or less “stable”, but are nonetheless a form of relationship in this new world of social media. And of course these relationships change frequently, so your points apply to this idea as well.

    Does Gist (or any other tool) have a way to measure how many people you’ve interacted with on Twitter in the last X days? Ideally this would be customized to measure @reply/@mention to or from the person, or both (presumably indicating slightly deeper relationship). This kind of data analysis would go a long way into exploring applicability of the Dunbar number to social media or whether or not a new concept is needed.

    1. Eric –
      These are great comments. I agree that the relationships you form in social networks are similar, and yet somewhat different, than the “stable social relationships” that Dunbar describes. These “loose ties” are the key to linking people within networks (something that Malcolm Gladwell writes about in The Tipping Point), yet over time many of them do mature into stable social relationships.

      I haven’t seen the feature you described that would measure social interactions over the last X days; there are some tools that will tell you this information for email, so I think that the analysis is coming soon. The bigger UI/UX question is helping people to make actionable decisions based on that data.

      If you have some specific product ideas in this area about Gist, please send them via email to



  5. I wonder how many people (or twitter handles) I could write down I sat down with a blank sheet of paper for 20 minutes. If given profile photos, I bet I could name at least 300 of them. I do think my “desk Dunbar number” is much larger than my street Dunbar number. For me, those two contexts seem more distinct than the slightly changing lense from one social network to another.

    1. Adam –
      You raise a great point, which is the availability of mnemonics (profile pictures, avatars, or other memory devices) to jog the memory and increase the likelihood of pulling these names from medium- or long-term memory.

      As we begin to have Heads Up Displays in other mediums (on glasses, anyone?) I can definitely envision a time when your distinction between “desk” Dunbar number and “street” Dunbar number becomes smaller. Smartphones also have made me much more able to remember who someone is and how I know them — I think there are more innovations ahead.

      Thanks for your thoughts.


  6. I think it would be interesting to study how many relationships one maintains during a given period of time and assign a number or category to each indicating the depth of the relationship interaction. I might only see or talk to my best friend once every couple of months, but when I do I share the deepest, most intimate part of myself so that relationship resonates longer than a 140 character interaction on Twitter.

    I think your age, how much you move around in your work or in your home life, how many social networks you are part of, what you do to maintain your relationships and what you expect to give/receive in a relationship would all influence how many people you actually have a stable relationship with. The number of 150 in real life relationships seems very low in that I have work, church, parenting, volunteer work, neighbors, family and friends of the 25 years of adult life I’ve lived in Seattle.

    I’ve found as I’ve grown older that people come and go from my life. But when they return, it’s easy to immediately return to the level of the bond that was there prior to the gap in connection. (Ex. eLiz and I). Facebook and LinkedIn have helped me stay connected with people that I might not have seen for years and in pre-social media times I would have lost as friends. For example I recently reconnected with a college friend whom I hadn’t spoken with for 25 years. The trust level was immediately there in our on-line interactions and when we reunited in person, it was as if time apart had never happened.

    The interesting thing happening on Twitter is that there are people who I never had met in person, who I used to have a lot of 140 character conversations with a couple of years ago. We’ve followed each other for more than 2 years, so you might think that we had some level of tie. But many of those early twitter users took the path of following everyone back who followed them and grew to have 10’s of thousands of followers. What I notice about these people is that they don’t respond to me the way they used to. They simply have to many messages coming in from followers and I’m just one more avatar. So back to Dunbar — I think that you can have about 500 – 1000 people on Twitter that you actually know something about who they are and what they are interested in. I follow about 1,000. And while I don’t know all of them, I have interacted with most of them on more than one occasion, and I’d bet I could tell you something about each of the people I follow should I look at their profile.

    My current approach to building twitter relationships is to focus on people I might actually meet — like you — or who share common interests or friends. It was fun 2 years ago to find new “friends” in Mumbai, Australia and Bejing. But the quality interactions I have on Twitter are with people I’ve really met or spoken to — and that number is more like 100 (and growing.)

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