Function Point Effort Calculator
Turn a function point count into effort using your own delivery rate.
In short
Turn a function point count into effort using your own delivery rate.
Formula: Effort hours = Function points × Your hours per function point; Person-months = Effort hours ÷ Hours per person-month
What this calculator does
Size × delivery rate, the standard function point estimating step. The delivery rate must be the organisation's own; no published or average rate is offered.
Use it to turn Function points to build, Your own hours per function point, Hours in one person-month into a checked result you can compare, copy, or rerun with different assumptions.
The page shows the formula, a numeric worked example, and the assumptions that affect this professional & industry calculation.
Inputs and what they mean
- Function points to build
- — number value.
- Your own hours per function point
- — Taken from your own completed projects. No industry rate is supplied..
- Hours in one person-month
- — number value.
How to use it
- Enter your own figures — the calculator never fills in a rate, price or benchmark for you.
- Press Calculate to see the result.
- Read the formula, variables, assumptions and source below the result before you rely on it.
Formula
Effort hours = Function points × Your hours per function point; Person-months = Effort hours ÷ Hours per person-month.
Inputs used: Function points to build, Your own hours per function point, Hours in one person-month.
Edge handling: Function points to build is required.; Function points to build cannot be negative.; Function points to build must be no more than 1000000000.; Your own hours per function point is required.; Your own hours per function point cannot be negative..
Worked example
480 function points at your own 13 hours per point
- Start with Function points to build: 480, Your own hours per function point: 13, Hours in one person-month: 152.
- Apply the method: Effort hours = Function points × Your hours per function point; Person-months = Effort hours ÷ Hours per person-month.
- The delivery rate comes from your own history, so the estimate stays yours.
Reading the result
The headline figure is the main answer. Any breakdown underneath shows the parts that make it up, so you can check the working and see what changes when you adjust an input.
Limitations and assumptions
- Inputs outside the supported range are rejected rather than forced into a result.
- The result depends on the values you enter for this function point effort calculator; it does not supply missing rates, rules, prices, dates, or assumptions for you.
Reference: International Function Point Users Group — Function Point Counting Practices
Last reviewed:
Common questions
Where does this formula come from?
IFPUG, Function Point Counting Practices Manual — functional size is counted independently of technology, and delivery rate is effort per unit of functional size. See the source link on this page.
What kind of calculation is this?
Functional size is multiplied by the organisation's own measured delivery rate. Check the formula, example, and limitations on this page before using the result for a real professional & industry decision.
What are its limits?
An estimate, not a commitment; accuracy depends entirely on the delivery rate entered. Does not model schedule or team size.
How do I use the Function Point Effort Calculator?
Enter the required values for Function points to build, Your own hours per function point, Hours in one person-month. The calculator applies the formula on this page and shows the main result with any supporting breakdown so you can check the arithmetic.
What formula does the Function Point Effort Calculator use?
Effort hours = Function points × Your hours per function point; Person-months = Effort hours ÷ Hours per person-month The visible formula section above lists the calculation path and the edge cases the page handles, so the result can be checked without relying on the form alone. Check the formula, example, and limitations on this page before using the result for a real professional & industry decision.
Can the Function Point Effort Calculator be used for exact decisions?
Use it as a calculation aid, not as a substitute for checking the underlying rule, contract, policy, or professional advice that applies to your situation. When a result depends on local rules, personal details, prices, or dates, enter those values yourself and confirm them before acting.
Formula, source and verification
Functional size is multiplied by the organisation's own measured delivery rate.
The question it answers: How much effort will this take, given how fast we actually deliver?
The formula
Effort hours = Function points × Your hours per function point; Person-months = Effort hours ÷ Hours per person-month
- FP — Function points to build
- (FP). Unadjusted function points counted for the planned software.
- r — Hours per function point
- (h/FP). The organisation's own delivery rate, from its completed projects.
- h_m — Hours in one person-month
- (h). The hours the organisation counts as one person-month.
Units: Function points; hours per function point; hours.
What kind of calculation this is
Estimation model. This is a published estimation model. It produces an estimate, not a measured fact, and its accuracy depends on how well your situation matches the model.
Method
Size × delivery rate, the standard function point estimating step. The delivery rate must be the organisation's own; no published or average rate is offered.
Assumptions built into the result
- Mathematical: The delivery rate came from work comparable to the work being estimated.
Figures this calculator will never guess for you
- No industry delivery rate, productivity figure, defect rate or cost per line is inserted.
- No optional component is filled in on the user's behalf.
- No default hours-per-function-point value is provided.
Limitations
- An estimate, not a commitment; accuracy depends entirely on the delivery rate entered.
- Does not model schedule or team size.
Source and version
- Standard or reference
- Function point analysis — delivery rate measures — International Function Point Users Group (IFPUG, Function Point Counting Practices Manual — functional size is counted independently of technology, and delivery rate is effort per unit of functional size.)
- Published source
- International Function Point Users Group — CPM 4.3.1 family
- Formula version
- Version 1
- Verification
- Reviewed against the cited source on
- How much weight the source carries
- Standards or government
- Applies to
- Currency
- The result is a ratio or index, so it does not depend on currency.
Cite this page
Free Calculator. (2026, September 16). Function Point Effort Calculator. https://freecalculator.tech/tools/function-point-effort-calculator
"Function Point Effort Calculator." Free Calculator, 16 Sept. 2026, https://freecalculator.tech/tools/function-point-effort-calculator.
Function Point Effort Calculator — Free Calculator, https://freecalculator.tech/tools/function-point-effort-calculator
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