Understanding Function Point Effort
How we calculate. Person-hours = FP × historical hours per function point. The form uses the same arithmetic as the worked examples on this page. See our methodology and accuracy policy.
Real-world scenario: A typical Function Point Effort case uses function points 320 and hours per function point 8. Enter the same figures below to reproduce the worked path.
What is Function Point Effort?
IFPUG-style sizing converted to effort via an org productivity factor. Calibrate hours/FP from completed projects.
- Use adjusted FP when VAF is applied
- Hours/FP must come from your history
- Divide by 152 (approx.) for person-months if needed
The Formula
Worked Example
Common Use Cases
- Fixed-bid sizing: FP-based quotes
- Vendor compare: productivity rates
- Backlog sizing: enhancement FP
Pro Tips
- Don’t borrow industry averages blindly
- Separate new vs enhancement FP
- Track actuals to recalibrate
Limitations: Function Point Effort results are educational software estimation aids—not bids, contracts, or performance scores. Calibrate models to your organization’s history.
FAQ
Unadjusted or adjusted FP?
Either—be consistent with how you measured hours/FP historically.
How do I get hours per FP?
From closed projects: actual hours ÷ delivered FP.
Authoritative References
For estimation and quality models, consult:
- COCOMO — Constructive Cost Model overview
- IFPUG — function point standards
- SEI / Carnegie Mellon — software engineering practice