Dunbar’s Number
You can’t maintain meaningful relationships with 5,000 LinkedIn connections. Your brain literally can’t.
Dunbar’s Number (~150) is the cognitive limit on stable social relationships—people you actually know, not just recognize. Robin Dunbar derived it from the correlation between primate brain size and social group size.
This number has held across tribes, military units, and companies. It’s biology, not preference.
The Layers
Relationships aren’t binary. They exist in concentric circles with hard capacity limits:
| Layer | Size | Description | Contact Frequency |
|---|---|---|---|
| Intimate | ~5 | Your closest people. Would call at 3am in crisis. | Daily/Weekly |
| Close Friends | ~15 | Strong emotional connection. Confide in regularly. | Weekly/Monthly |
| Friends | ~50 | Would invite to a group dinner. Know well. | Monthly |
| Acquaintances | ~150 | ”Meaningful” relationships. Would recognize at a party. | Occasionally |
| Recognizable | ~500 | Would recognize face/name. No real relationship. | Rarely |
| Known Faces | ~1,500 | Can attach a name to a face. That’s it. | Never |
Each layer is ~3× the previous (5 → 15 → 50 → 150 → 500 → 1,500). This reflects the cognitive cost of each intimacy level.
Why This Matters
Quality beats quantity. Life satisfaction correlates with your inner circles (5-15), not your follower count. 2,000 LinkedIn connections ≠ 2,000 friends.
Relationship investment is zero-sum. Every hour on weak ties is an hour not spent deepening strong ones. Are you investing in the right layer?
The modern paradox. More connections than ever. More loneliness than ever. We’ve expanded outer circles while starving inner ones. 500 Instagram followers doesn’t replace 5 close friends.
The Inner 5
Your life-or-death relationships:
- Would help you move a body (metaphorically)
- Know your real struggles, not your highlight reel
- You’d drop everything for them, and they for you
Requires hours per week and mutual vulnerability. Often: partner, best friends, close family.
The problem: Most people’s inner circle has atrophied. Lots of acquaintances, no one to call in crisis.
The Close 15
Your go-to people:
- You’d attend their wedding, visit them in hospital
- Real conversations, not surface chatter
- Know each other’s lives in detail
Requires weekly to monthly contact. The “dinner party” group.
The problem: Gets crowded out by obligatory relationships that don’t actually support you.
The Outer Layers (50-150)
Friends (50): Would invite to a party. Real conversations when you meet. Need periodic maintenance.
Acquaintances (150): Dunbar’s original number. You know who they are and how they relate to others. The natural size of tribes, military units, and functional companies.
What To Do
Audit your circles:
- Who would you call at 3am? → Inner 5
- Who do you share real struggles with? → Inner 5
- Who would you host for a weekend? → Close 15
- Who do you genuinely enjoy? → Friends 50
If your inner circles are sparse, that’s where to focus. Not LinkedIn.
Invest intentionally:
- Identify your target 5
- Invest disproportionately—hours, not minutes
- Prune draining obligatory relationships
- Accept the limit. You can’t be close with everyone.
Social media: Useful for the 150-500 layer. Harmful if it substitutes for 5-15. Likes aren’t relationships.
Why Organizations Break at 150
- Small companies feel different—everyone knows everyone
- Military companies are ~150 soldiers
- Villages stabilized around 150 people
- Startups lose culture when they cross 150 employees
Beyond 150, informal relationships can’t hold the group together. You need hierarchy.
Related
- Friendship Maintenance — The protocol
- The Giver’s Paradox
You cannot have 1,000 friends. You can have 5 close friends and 145 acquaintances.
5,000 LinkedIn connections and no one to call in crisis = wrong metric. Depth beats breadth.