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Brooks's Law
Adding Manpower to a Late Project Makes It Later
"The bearing of a child takes nine months, no matter how many women are assigned."
— Fred Brooks, The Mythical Man-Month (1975)
📊 The "Man-Month" Myth
Fred Brooks observed that software project managers make a critical error: treating people and time as interchangeable. If 5 people can finish in 10 months, surely 10 people can finish in 5 months?
Wrong. Complex projects can't be perfectly partitioned. Adding people adds communication overhead, training time, and coordination costs. The formula for communication paths is n(n-1)/2—doubling the team quadruples the communication!
🔗 Communication Paths Visualization
💥 Real-World Examples
IBM OS/360
$500M → $1B+
Brooks's own disaster. Team grew to 1,000 people. Missed every deadline. "Adding more programmers made it later."
Healthcare.gov (2013)
55 contractors, 6 weeks late
Too many teams, no clear ownership. Required emergency rescue team of just 6 developers to fix it.
Microsoft Windows Vista
5 years, 50M lines of code
Massive team coordination problems. "Longhorn Reset" scrapped years of work. Delayed 2+ years.
FBI Virtual Case File
$170M wasted, 0 delivered
Team kept growing, complexity exploded. Entire project cancelled. "A lesson in how not to build software."
✅ Mitigations & Solutions
The "Two-Pizza Rule"
Jeff Bezos: Teams should be small enough to feed with two pizzas (6-8 people max).
Add People Early
Brooks's Law only applies to late projects. Adding people early allows proper ramp-up time.
Modular Architecture
Design systems with clear interfaces. Independent modules reduce communication needs.
The Bermuda Plan
Sometimes the answer is removing people: "Send half the team to Bermuda" and let experts finish.