Understanding COCOMO Schedule
How we calculate. Schedule months = 2.5 × person-months^0.38. The form uses the same arithmetic as the worked examples on this page. See our methodology and accuracy policy.
Real-world scenario: Effort estimate of 100 person-months. Use those inputs in the COCOMO Schedule form to verify the on-page formula.
What is COCOMO Schedule?
Nominal schedule from Basic COCOMO. Compressing below this increases risk and often cost.
- PM = person-months of development effort
- Output is calendar months of development
- Staffing ≈ PM ÷ months as a rough average
The Formula
COCOMO Basic Schedule
Duration (months) = 2.5 × (PM)^0.38
Worked Example
Scenario: Effort estimate of 100 person-months.
Step 1: PM = 100
Step 2: 100^0.38 ≈ 5.75
Step 3: Schedule = 2.5 × 5.75 ≈ 14.39 months
Answer: Nominal schedule is about 14.39 months.
Common Use Cases
- Roadmaps: first-pass timelines
- Staffing: average headcount hints
- Risk talks: aggressive compression
Pro Tips
- Don’t force impossible compression
- Add integration/test buffers outside the model
- Use with effort estimate
Limitations: COCOMO Schedule results are educational software estimation aids—not bids, contracts, or performance scores. Calibrate models to your organization’s history.
FAQ
Is this calendar time or work months?
COCOMO schedule is development duration in months; staffing is a separate decision.
What if PM is 0?
Schedule is 0—enter positive effort.
Authoritative References
For estimation and quality models, consult:
- COCOMO — Constructive Cost Model overview
- IFPUG — function point standards
- SEI / Carnegie Mellon — software engineering practice