---
id: "concept-dunbars-number"
type: "concept"
source_timestamps: ["¶2"]
tags: ["anthropology", "scaling-thresholds"]
related: ["claim-decision-making-fractures", "concept-bermuda-triangle-management"]
definition: "The cognitive limit of ~150 individuals for maintaining stable social relationships, marking the point where formal organizational mechanisms become mandatory."
sources: ["tail1"]
sourceVaultSlug: "hbr-seg-tail1"
originDay: 1
articleStem: "hbr-tail-105-fast-growing-better-decisions"
sourceUrl: "https://hbr.org/2026/05/how-fast-growing-companies-can-make-better-decisions"
sourceTitle: "How Fast-Growing Companies Can Make Better Decisions"
---
# Dunbar's Number in Organizations

Originating in anthropology, **Dunbar's number (approximately 150)** represents the cognitive limit for maintaining stable social relationships.

Applied to organizational growth, reaching **~150 employees** marks the point where informal, relationship-based management **completely breaks down**, making formal mechanisms and management systems an absolute requirement for survival. This is the upper anchor of the fracturing thresholds described in [[claim-decision-making-fractures]] and helps explain why companies enter the [[concept-bermuda-triangle-management|Bermuda Triangle of Management]].

> **Enrichment.** The link is directionally consistent with the idea that social-cognitive limits constrain informal coordination, but Dunbar's original work concerns *stable social relationships*, not a hard organizational rule. Treat ~150 as a heuristic, not a law.