capacity-planning

Capacity Planning

Project realistic team capacity across multiple quarters to set achievable roadmaps and hiring needs.

Context

You are helping a tech lead forecast capacity for the next 2-4 quarters. If you have team size, hiring plans, or attrition history, use that data to ground the model.

Domain Context

• Larson's "An Elegant Puzzle" emphasizes team size as the primary lever for capacity change
• Reilly's "The Staff Engineer's Path": capacity planning must account for ramp time (new hires are 40-60% productive for 2-3 months)
• Research on team velocity: adding headcount doesn't linearly increase output due to communication overhead (Brooks' Law)

Key principles:

1. Headcount is destiny: Team capacity is determined almost entirely by team size, not optimization magic
2. New hires carry ramp cost: Budget 2-3 months at 40-60% productivity per new person, plus mentoring load on existing team
3. Attrition is normal: Plan for 10-15% annual attrition; losing a senior person costs ~3 months of productivity across team knowledge loss

Instructions

1. Baseline current capacity: Calculate your team's proven velocity (stories/points per sprint, or features per quarter). If new, estimate conservatively: 40 stories/quarter for a 6-person team
2. Model quarterly scenarios: Build three columns: headcount at quarter start, expected headcount at end (after hiring/attrition), and estimated velocity
3. Account for ramp time: For each new hire, reduce team velocity by 1-2 person-weeks for the month they start, plus 0.5 person-weeks for mentoring
4. Model attrition risk: If you lose a senior engineer, mark that quarter as -20% velocity. If you lose a mid-level engineer, -10%
5. Add contingency: Historical data shows 15-20% of plans get disrupted by incidents, support, or surprise work. Plan for 80-85% of theoretical capacity as available
6. Map to roadmap items: Take your roadmap (from technical-roadmap skill) and assign effort estimates. Does it fit in the available capacity windows? If not, prioritize or extend timeline
7. Make staffing cases: Identify roadmap items that require hiring to complete. Build business cases for each hire ("shipping feature X requires 2 more backend engineers in Q2")

Anti-Patterns

• Ignoring ramp time: LLMs often assume new hires contribute immediately. Reality: junior engineers are 30% productive for 3 months, mid-level 60% productive for 2 months. Always deduct.
• Confusing team size with team output: Adding 1 person doesn't add 20% capacity; communication overhead usually limits gains to 10-15%. LLMs often assume linear scaling.
• Planning without attrition: Most capacity plans ignore the 10-15% annual attrition rate. If your team has 5 people, plan for losing ~1 person per year.
• Forgetting mentoring load: When you hire, the team's productivity drops because senior people spend time onboarding. LLMs often plan as if mentoring is free.

Further Reading

• Larson, Will. "An Elegant Puzzle." Chapter on hiring and capacity.
• Brooks, Frederick. "The Mythical Man-Month." Addison-Wesley, 1975. Chapter on communication overhead.
• Reilly, Tanya. "The Staff Engineer's Path." Chapters on hiring and team composition.