Definition of Dunbar's number in English:

Dunbar's number

(also Dunbar number)


  • A theoretical limit to the number of people with whom any individual is able to sustain a stable or meaningful social relationship (usually considered to be roughly 150)

    ‘even in the age of Facebook, the number of friends with whom you keep in touch is likely to be less than Dunbar's number’
    • ‘It seems like electronic communications and social networks are increasing Dunbar's Number such that it's now somewhat divorced from neocortical size.’
    • ‘Recent study into how social networking sites affect Dunbar's number indicates that that advances in technology have not been matched by changes in mental capacity.’
    • ‘Lately, Dunbar's number has been taken as a mean size for online networks and groups.’
    • ‘Recall that the Dunbar number is what you can manage with your own faculties, so somehow you are cognizant of your active network.’
    • ‘Technically "Dunbar's number," a theoretical limit that pegs the number of social relationships one can maintain at somewhere between 100 and 230, applied to everyone, but I couldn't help but take it personally.’
    • ‘Second, to summarize, Dunbar's Number says that we can only have a fixed number of relationships in life.’
    • ‘The second category of respondents (28 percent) follow more than 250 feeds, which is much higher than the Dunbar number.’
    • ‘The Dunbar number probably dates back to the appearance of anatomically modern humans 250,000 years ago.’
    • ‘I've maintained in the past that the future of humanity lies in small communities (Dunbar's number, maximum) which provided from within themselves all that their members might need.’
    • ‘People have a limit on the number of relationships they can keep in their heads - recognizing people, knowing about them, knowing their relationships to each other. Dunbar's Number puts a name to this limit.’
    • ‘Psychological studies have confirmed that human groupings naturally tail off at around 150 people: the 'Dunbar number', as it is known.’
    • ‘So, Chris is thinking about his Dunbar number, the point at which the 300+ relationships on his social network sites don't scale.’


Early 21st century: named after Robin Dunbar (b. 1947), the British anthropologist and psychologist who proposed the theory in the 1990s.