# Function Point Count Calculator > Size a software application from its data and transaction functions before estimating effort or cost. Page: https://freecalculator.tech/tools/function-point-estimate-calculator Last reviewed: 2026-09-15 ## How do I calculate unadjusted function points? Multiply the counts of external inputs, external outputs, external inquiries, internal logical files and external interface files by their IFPUG complexity weights, then add the five subtotals. No value adjustment factor is applied. ## Formula UFP = Σ (count × weight) over external inputs, external outputs, external inquiries, internal logical files and external interface files - For each function type, multiply its low, average and high counts by the corresponding weights, then add all five subtotals. - External inputs (EI): low × 3 + average × 4 + high × 6. External outputs (EO): low × 4 + average × 5 + high × 7. - External inquiries (EQ): low × 3 + average × 4 + high × 6. Internal logical files (ILF): low × 7 + average × 10 + high × 15. - External interface files (EIF): low × 5 + average × 7 + high × 10. The sum is unadjusted function points (UFP); no value adjustment factor is applied. - UFP = Σ (count × weight) over external inputs, external outputs, external inquiries, internal logical files and external interface files. - Inputs used: External inputs — low complexity, External inputs — average complexity, External inputs — high complexity, External outputs — low complexity, External outputs — average complexity, External outputs — high complexity, External inquiries — low complexity, External inquiries — average complexity, and other shown inputs. ## Inputs - External inputs — low complexity - External inputs — average complexity - External inputs — high complexity - External outputs — low complexity - External outputs — average complexity - External outputs — high complexity - External inquiries — low complexity - External inquiries — average complexity - External inquiries — high complexity - Internal logical files — low complexity - Internal logical files — average complexity - Internal logical files — high complexity - External interface files — low complexity - External interface files — average complexity - External interface files — high complexity ## Worked example: Application with mixed complexity The existing example counts produce 108 unadjusted function points, with every weighted subtotal shown below. 1. External inputs: 5 low × 3 + 3 average × 4 + 1 high × 6 = 33 FP. 2. External outputs: 4 low × 4 + 2 average × 5 + 1 high × 7 = 33 FP. 3. External inquiries: 3 low × 3 + 1 average × 4 + 0 high × 6 = 13 FP. 4. Internal logical files: 2 low × 7 + 1 average × 10 + 0 high × 15 = 24 FP. 5. External interface files: 1 low × 5 + 0 average × 7 + 0 high × 10 = 5 FP. 6. Total UFP = 33 + 33 + 13 + 24 + 5 = 108 FP. No adjustment factor or productivity rate is applied. ## Common questions ### How do I calculate unadjusted function points? Multiply the counts of external inputs, external outputs, external inquiries, internal logical files and external interface files by their IFPUG complexity weights, then add the five subtotals. No value adjustment factor is applied. ### What does a function point calculator measure? It measures functional size in unadjusted function points (UFP). Each function count is multiplied by its IFPUG type-and-complexity weight, and the five subtotals are added. ### What are EI, EO, EQ, ILF and EIF? EI are external inputs that maintain data from outside the application boundary; EO send derived data outside it; EQ are retrieval-only inquiries. ILF are user-identifiable data groups maintained inside the boundary, while EIF are referenced data groups maintained elsewhere. ### How do I choose low, average or high complexity? Identify the function and classify it under the applicable IFPUG Counting Practices Manual rules before entering its count. This calculator applies the selected weights; it does not infer complexity from a screen count or application description. ### Are these adjusted or unadjusted function points? The result is unadjusted function points. No value adjustment factor is applied to the weighted sum. ### Can function points directly give project effort or cost? No: function points measure functional size, not hours or money. Effort and cost need a separately justified, organisation-specific productivity rate and any relevant cost inputs. ## Limitations and assumptions - Functions must already be identified and classified under the IFPUG counting rules. The calculator does not determine complexity from requirements, screens or source code. - The result is unadjusted function points, not person-hours, project cost or source lines of code. Those estimates require separately justified conversion or productivity assumptions. - No value adjustment factor, productivity benchmark or price is assumed. - 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 count calculator; it does not supply missing rates, rules, prices, dates, or assumptions for you. ## Sources - IFPUG — https://www.ifpug.org/ifpug-standards/ ## Cite this page - APA: Free Calculator. (2026, September 15). Function Point Count Calculator. https://freecalculator.tech/tools/function-point-estimate-calculator - MLA: "Function Point Count Calculator." Free Calculator, 15 Sept. 2026, https://freecalculator.tech/tools/function-point-estimate-calculator. - Link: Function Point Count Calculator — Free Calculator, https://freecalculator.tech/tools/function-point-estimate-calculator