Dunbar's Number Calculator

What is Dunbar's Number?

Dunbar's number is one of the most fascinating findings in social anthropology: around 150 people — that is the natural upper limit of meaningful relationships a human can maintain simultaneously. This limit was discovered and described by British anthropologist Robin Dunbar in the early 1990s. Dunbar did not begin his research with human societies, but with primates: he found that the size of the neocortex — the brain region responsible for social cognition — directly correlates with the typical group size of a primate species. When he applied this method to humans, he arrived at a number of approximately 150.

This number keeps appearing: in the villages of traditional societies, in military units, in successful company departments, and in the size of friendships on social networks. Dunbar himself calls it a "cognitive-emotional capacity limit" — not the number of people we know, but the number of those with whom we can maintain genuine, reciprocal social awareness.

Why Your Dunbar Number Is Personal

150 is the scientific mean — but people are not average beings. Robin Dunbar has always emphasised in his research that this is a statistical distribution: some people maintain stable networks of 100, others of 200 relationships. What explains this variance is well documented:

• Age and life stage: Young people in education or university have structurally more peer contact. With increasing age — especially during the career and family peak between 36 and 50 — available social energy naturally declines. Studies show that people over 65 actively consolidate their social circles, choosing quality over quantity.
• Introversion and extroversion: Extroverted people invest less cognitive energy per social interaction. This doesn't mean they have deeper friendships — but they can maintain more outer relationships (acquaintances). Introverts often have comparable inner circles, but smaller outer layers.
• Work hours: Time is the currency of social life. Those who work 60 or more hours a week simply have less time for relationship maintenance — especially the middle layers, which require regular contact.
• Partnership and family: A close partnership "absorbs" a slot in the innermost layer — this is not a loss but a gain in depth. Small children consume cognitive and time resources that would otherwise be available for middle relationship layers.
• Moves and transitions: A relocation is the strongest short-term stressor for social networks. For up to 12–18 months after moving, the outer circle is measurably smaller — people who know this can actively counteract it rather than worrying about it.

The 6 Layers of Your Relationships

Dunbar's research revealed not just the 150 — it uncovered an entire layered model that follows a rule of 3x multiplication. Each outer layer is approximately three times as large as the inner one:

• Support Clique (5): The people you confide in during real crises. Typically your partner, your best friend, a sibling. No more than 5 — because genuine intimacy requires investment.
• Sympathy Group (15): Close family and best friends. You know these people well enough that you would call them spontaneously. They would attend your funeral.
• Close Friends (50): Good friends. You know what's happening in their lives; they know what's happening in yours. You meet several times a year.
• Good Friends (150): The Dunbar number. Meaningful contacts — people with whom a genuine social relationship exists, even if you rarely see each other.
• Meaningful Contacts (500): Acquaintances — you know their face, name, and context. You could wave at them on the street and have a brief conversation.
• Acquaintances (1500): The periphery — names and faces that come to mind without a genuine relationship behind them.

How Our Calculator Works

We want to be transparent: the Dunbar calculator is a reasoned approximation, not a scientific precision measurement. Robin Dunbar's research does not provide an individual number — it provides a distribution. Our calculator distils the published moderators (age, workload, introversion, family situation, mobility, social investments) into multipliers applied to the 150 baseline.

The multipliers are drawn from peer-reviewed studies on social network size variation (Dunbar & Sosis 2003, Roberts et al. 2009, Bhattacharya et al. 2016). The formula is:

personalised layer[i] = baseline[i] × ageFactor × workFactor × introversion × familyFactor × relationshipStatus × moveFactor × commitment

No algorithm replaces self-knowledge. Use your number as a starting point for reflection, not a verdict.

What to Do With Your Dunbar Number

Knowing your social capacity is not an invitation to resignation — it is an invitation to prioritise. If your capacity is 120, the question is not "I have too few friends," but: "Which 120 people deserve my conscious attention?"

Practical next steps:

• Write down your support clique (5). When did you last speak to each of them?
• Review your sympathy group (15). Is there someone you mentally place there, but haven't contacted in months?
• Accept the limits of the outer layers: you don't need to actively nurture every acquaintance. The layers exist because they require different intensities.

Endearist will help you tend these layers systematically — with gentle reminders that feel like human attention, not a CRM.

The Science Behind the Layers

The social brain hypothesis — the theoretical foundation of Dunbar's work — proposes that the evolution of primate intelligence was driven primarily by the demands of complex social life. Managing relationships requires remembering who owes favours to whom, tracking alliances and tensions, predicting behaviour, and maintaining trust over time. All of this requires neocortex capacity.

What makes Dunbar's finding so robust is its cross-cultural replication. The 150-person group size appears in hunter-gatherer band sizes, Hutterite colony splitting decisions (communities split when they exceed ~150 to preserve social cohesion), and even in the organisation of effective military units across history. The layers (5, 15, 50, 150, 500, 1500) have been replicated in studies of mobile phone call data, Twitter follower interactions, and historical village sizes.

For further reading: Dunbar, R. I. M. (1992). "Neocortex size as a constraint on group size in primates." Journal of Human Evolution, 22(6), 469-493. Available via DOI: 10.1016/0047-2484(92)90081-J.