In 1992, evolutionary psychologist Robin Dunbar proposed that the size of a primate's neocortex limits how many stable social relationships it can maintain. For humans, that ceiling lands around 150 — nested inside smaller, more intimate layers. Map your own relationships below and see how your social world compares.
Add real people into each layer and watch the rings fill. Everything is saved locally in your browser only — nothing is sent anywhere.
Dunbar plotted neocortex size against average group size across dozens of primate species and found a tight correlation. Extrapolating the human neocortex along that line predicts a group size of roughly 150 — the number of people a person can maintain genuine, stable social relationships with, where each party knows who the other is and how they relate to one another.
Dunbar's own model nests several layers of intimacy inside one another, each roughly three times the size of the one before — 5, 15, 50, 150.
A 2021 statistical reanalysis by Dunbar's own collaborators found the confidence interval on "150" spans roughly 100 to 250 — the method is sound, the point estimate less precise than the popular framing suggests.
Maintaining a relationship at any layer takes ongoing investment — conversation, shared experience, mutual favors. Layers erode when that investment stops, which is what this tool tries to make tangible.