Brooks's Law
Updated 2026-08-08
INTRODUCTION
English translation pending.
CORE DEFINITION
Brooks's Law states that assigning more people to a rushed development project only slows the schedule further. It was formulated by Frederick P. Brooks Jr., widely regarded as the father of the IBM 360 system, and appeared in The Mythical Man-Month. The core formula is that person-months equal persons multiplied by months, but months do not equal person-months divided by persons. In extreme form, pouring more people onto a delayed task makes the task even more delayed, because new hires add onboarding time and communication overhead that slow development in the short run, while many tasks are indivisible. The law warns managers against the temptation of brute-force staffing.
SCAFFOLDING EFFECT
Reduce cognitive load
- Counter the headcount reflex: treat adding people as a cost, not a fix, when behind schedule. - Forecast communication overhead: weigh training and coordination drag before approving hires. - Prefer alternatives first: use overtime, scope cuts or task splitting before adding staff.
Anchor fast decisions
Built on non-linear communication cost. Every added member brings training burden and communication paths that scale roughly with the square of headcount, so short-run velocity falls; and indivisible tasks cannot absorb extra people at all.
MINIMUM ACTION
In progress 0/1Practice this model in one real situation:
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Source support: Explicit
- en.wikipedia.orghttps://en.wikipedia.org/wiki/Brooks's_lawverified
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