Understanding COCOMO Basic Effort
How we calculate. Person-months = 2.4 × KLOC^1.05 (organic Basic COCOMO). See our methodology and accuracy policy .
Real-world scenario: A project estimated at 50 KLOC (organic). Use those inputs in the COCOMO Basic Effort form to verify the on-page formula.
What is COCOMO Basic Effort?
Classic Boehm COCOMO Basic organic model for relatively small, familiar projects. Intermediate/Detailed COCOMO add cost drivers not included here.
- Organic coefficients: a=2.4, b=1.05
- KLOC = thousands of delivered source lines
- Planning aid only—calibrate to your org
The Formula
Worked Example
Common Use Cases
- Early bids: ballpark staffing
- Portfolio compare: size vs effort
- Teaching: estimation models
Pro Tips
- Don’t use for embedded/semidetached without other modes
- Calibrate KLOC definition (comments? generated?)
- Pair with schedule model
| Scenario | When to use |
|---|---|
| Percent of a number | Finding a part of a whole (tax, tip, score) |
| Percent change | Comparing old vs new values |
Limitations: COCOMO Basic Effort results are educational software estimation aids—not bids, contracts, or performance scores. Calibrate models to your organization’s history.
Common mistakes
- Swapping part and whole: The denominator must be the full total, not a subset.
- Rounding too early: Carry extra decimal places through multi-step work before rounding the final percent.
- Mixing percent and decimal forms: Enter rates in the format the calculator labels expect.
The worked example for cocomo basic effort was verified with the calculator form on this page—enter the same values to confirm the result.
When to use this calculator
- Use this page when your wording matches cocomo basic effort and the form labels on screen.
- Use percent of a number for “what is X% of Y?” problems.
- Use number is what percent when you know part and whole and need the percent.
Still unsure about cocomo basic effort? Start with the quick answer above, then open the linked calculator that matches your wording.
❓ Frequently Asked Questions
How do I use this cocomo basic effort calculator?
For cocomo basic effort, enter the values labeled on the form, then press Calculate. Compare the result to the worked example on this page.
What formula does this page use?
See the quick answer and formula box above for cocomo basic effort—the same percentage calculator expression is applied to your inputs.
What if my result looks wrong?
When checking cocomo basic effort, re-check part vs whole (or rate vs base), rounding, and whether percents were entered as 25 rather than 0.25 when the form expects percents.
Authoritative References
For estimation and quality models, consult:
- COCOMO — Constructive Cost Model overview
- IFPUG — function point standards
- SEI / Carnegie Mellon — software engineering practice