“I have 600 contacts in my phone and still feel alone.” That sentence is not a contradiction, it is almost a logical consequence. Because the question of how many friends a person needs cannot be answered with one large number. It can only be answered in layers, and the innermost of them is surprisingly small. The anthropologist Robin Dunbar gave us one of the best known figures in social science for this. It is quoted constantly and almost always misunderstood.
Where the 150 comes from
In the 1990s, Dunbar noticed a pattern: the larger the neocortex of a primate species, the larger its average group. Apply the formula to humans and you arrive at about 150, the number of people with whom we can hold a stable, personal relationship at the same time. Not “know”. Hold. People whose identity you know and whose stance toward you you understand, and with whom the relationship does not fade if you do nothing.
Dunbar later found 150 again surprisingly often: in the typical size of Neolithic villages, in military companies, in the headcount at which firms begin to need formal hierarchies, in the average size of Christmas card lists. His 1993 work made 150 the popular ceiling for meaningful relationship maintenance.
An honest framing belongs here: the exact number is contested in the research. A 2021 re-analysis arrives, depending on method, at values between 70 and over 500 and considers a single number untenable. For everyday life that hardly matters, because the genuinely interesting part lies not in the ceiling but in what sits beneath it.
The layers count, not the sum
Dunbar's network is not a flat circle but a series of nested shells. Each outer layer is larger but emotionally thinner. And the farther out it sits, the less it contributes to your wellbeing.
The decisive message: when you feel lonely, the 150 is almost never the problem. It is the 5. You can have a full outer network and an empty core. That is exactly what explains why popular personalities or people with a large circle of acquaintances can be deeply lonely. The shell is right, the core is missing.
So how many close friends do you need?
The honest answer from the research: fewer than most people think, and it is quality, not quantity. Studies on subjective wellbeing show with remarkable consistency that even a small number of truly close relationships delivers most of the social protective effect. Someone with three to five people they can confide in is far better buffered against stress and depressive episodes than someone with fifty superficial contacts.
Beyond a point, more is not better, just more expensive. Every close relationship costs time and attention, resources that are finite. The communication researcher Jeffrey Hall measured in 2019 how much shared time friendship requires: around 50 hours to a casual acquaintance, about 90 to a friendship, and over 200 hours before someone becomes a close friend. That time cannot be multiplied at will. Whoever tries to maintain fifty close friends ends up maintaining none of them properly.
How many shared hours friendship costs
Why friendships quietly disappear
The treacherous thing about the innermost layer is that it shrinks without care, and it does so unnoticed. Relationships you do not invest in slowly slide outward. The confidant becomes the good friend, the good friend becomes the Christmas card. No one decides this actively. It happens through omission, usually in life phases with little slack: after a move, with small children, in a demanding job. How strongly the social network changes precisely in midlife is something we describe in the piece (article: innerpulse/blog/2026/11/loneliness-after-40 text: “Loneliness after 40”).
That is exactly why it pays to keep a conscious eye on your own core rather than relying on gut feeling. Whoever regularly tracks how they are doing and whom they spend time with notices sooner when the innermost ring is drying out, often weeks before the loneliness shows up as a diffuse low mood. Why this social factor weighs so heavily is something we explain at a fundamental level in (article: innerpulse/blog/2026/05/loneliness-and-mental-health text: “Why loneliness hits the mind so hard”).
What you can practically do with Dunbar's number
The research translates into a few concrete attitudes:
- Invest inward, not outward. When you have social energy, give it to the three to five people closest to you. One deepened relationship does more than ten new contacts.
- Accept that not everyone can stay. It is not a failure when former close friendships drift outward. Layers are permeable in both directions. All that matters is that the innermost ring does not run empty.
- Create shared time, not just shared occasions. The 200-hour rule means: regularity beats the grand reunion. A weekly call builds more than the annual class get-together.
- Do not measure the size, measure the depth. The question is not “How many people do I know?” but “Who would I call at 3 in the morning, and would they know they would be picked up?”
How InnerPulse helps
Social connection is one of the strongest levers for mood, but also one of the most inconspicuous. (article: innerpulse/blog/2026/04/innerpulse-guide text: InnerPulse) makes it visible: you log your mood daily and note whom you spent time with. After a few weeks your data shows which kind of contact really carries you, and whether the days with real conversations reliably sit above the others. The app calculates that automatically. No subscription, no cloud, no data that leaves your device.
In the end, Dunbar's number is not a call to collect 150 contacts. It is permission to focus on a few. You do not need a large network. You need a load-bearing core.
This article is for information and does not replace medical or psychotherapeutic advice.
Further reading
- (article: innerpulse/blog/2026/05/loneliness-and-mental-health text: Why loneliness hits the mind so hard) is the big overview.
- (article: innerpulse/blog/2026/11/loneliness-after-40 text: Loneliness after 40) explains why the network changes in midlife.
- (article: innerpulse/blog/2026/04/positive-events-mental-health text: The quiet effect of good days) shows why small, recurring contacts carry.
- (article: innerpulse/blog/2026/04/how-alone-am-i-with-my-problem text: How alone am I with my problem?)
- (article: innerpulse/blog/2026/10/solitude-vs-loneliness text: Good solitude, bad loneliness): why a smaller network does not automatically make you lonely.
- Dunbar (1993): Coevolution of Neocortical Size, Group Size and Language in Humans
- Lindenfors et al. (2021): “Dunbar's number” deconstructed
- Hall (2019): How many hours does it take to make a friend?