Function Point Count Calculator
Size a software application from its data and transaction functions before estimating effort or cost.
What this calculator does
Each identified function is weighted by type and complexity using the published IFPUG counting weights, then summed. The counter classifies each function as low, average or high complexity and enters the counts. The calculator applies only the published weights; it does not guess complexity and it applies no value adjustment factor.
Inputs and what they mean
- Low
- — number value.
- Average
- — number value.
- High
- — number value.
- Low
- — number value.
- Average
- — number value.
- High
- — number value.
- Low
- — number value.
- Average
- — number value.
- High
- — number value.
- Low
- — number value.
- Average
- — number value.
- High
- — number value.
- Low
- — number value.
- Average
- — number value.
- High
- — 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
UFP = Σ (count × weight) over external inputs, external outputs, external inquiries, internal logical files and external interface files
Worked example
Application with mixed complexity
Counts classified low, average and high for each function type.
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
Results depend entirely on the figures you enter and are rounded for display. They are for general information and education, not professional advice.
Reference: IFPUG — Function Point Counting Practices
Last reviewed:
Common questions
Formula, source and verification
Each identified function is weighted by type and complexity using the published IFPUG counting weights, then summed.
The question it answers: How big is this application in terms the business can compare across projects?
The formula
UFP = Σ (count × weight) over external inputs, external outputs, external inquiries, internal logical files and external interface files
- EI — External inputs
- (count). Processes that maintain data from outside the boundary.
- EO — External outputs
- (count). Processes that send derived data outside the boundary.
- EQ — External inquiries
- (count). Retrieval-only processes.
- ILF — Internal logical files
- (count). User-identifiable data groups maintained inside the boundary.
- EIF — External interface files
- (count). Data groups referenced but maintained elsewhere.
Units: Function points (dimensionless counts).
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
The counter classifies each function as low, average or high complexity and enters the counts. The calculator applies only the published weights; it does not guess complexity and it applies no value adjustment factor.
Assumptions built into the result
- Industry: Functions have already been identified and classified by a counter.
Figures this calculator will never guess for you
- No productivity rate, hours per function point, or cost is assumed here.
Limitations
- Gives unadjusted function points only. Effort and cost need a separate, organisation-specific productivity rate.
Source and version
- Standard or reference
- Function Point Analysis (Counting Practices Manual) — IFPUG (IFPUG Counting Practices Manual, unadjusted function point weights by function type and complexity.)
- Published source
- IFPUG — 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.
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