{ "category": "Financial functions", "display_name": "PDURATION", "entry_kind": "built_in_function", "eval_api": { "method": "POST", "url": "https://handbook.dnacalc.com/api/eval" }, "function_id": "FUNC.PDURATION", "implementation_state": { "answer_bank": { "excel_builds": [ "20430" ], "larger_numeric": 0, "last_bit": 0, "matched": 1205, "other_mismatch": 0, "refused": 0, "rows": 1205, "unread": 0, "worst_ulp": 0 }, "detail": "Recorded: 1,205 in the answer bank and 5 workbook cells.", "dnacalc_commit": "9e1884369a678158dd82d3d74188daf986995e87", "in_catalogue": true, "state": "matches", "state_label": "Matches every recorded Excel answer", "summary": "Matches all 1,210 recorded answers", "workbook_corpus": { "cells": 5, "matched": 5 } }, "implementations": [ { "commit": "9e1884369a678158dd82d3d74188daf986995e87", "flavour": "excel-compatibility-candidate", "language": "Rust", "name": "CalcFunc", "own_code": [ "https://github.com/DnaCalc/DnaCalc/blob/9e1884369a678158dd82d3d74188daf986995e87/crates/calc-func/src/catalogue/financial.rs#L210-L212", "https://github.com/DnaCalc/DnaCalc/blob/9e1884369a678158dd82d3d74188daf986995e87/crates/calc-func/src/ported/financial_time_value_family.rs#L1108-L1128" ], "repository": "https://github.com/DnaCalc/DnaCalc", "shared_code": [ "catalogue/financial::tv_out", "ported/financial_time_value_family::validate_finite" ], "source": "https://github.com/DnaCalc/DnaCalc/blob/9e1884369a678158dd82d3d74188daf986995e87/crates/calc-func/src/catalogue/financial.rs#L210-L212", "state": "matches", "suite": null, "summary": "Matches all 1,210 recorded answers" } ], "json_url": "https://handbook.dnacalc.com/api/functions/FUNC.PDURATION.json", "name": "PDURATION", "notes": [], "schema": "efh.function-reference/v1", "section_order": [ "what-it-does", "try-it", "quirks", "how-to-implement", "version-differences", "alternatives" ], "sections": { "alternatives": "\n[NPER](FUNC.NPER.md) includes periodic payments; [RRI](FUNC.RRI.md) solves a growth rate from a period count; [FV](FUNC.FV.md) solves the resulting balance.\n\n\n", "how-to-implement": "\nLet `D` denote ordinary nearest/even binary64 storage. The current graph uses three separate [public worksheet LN](FUNC.LN.md#how-to-implement) results:\n\n1. Validate finite, strictly positive rate, present value and future value.\n2. Obtain `Lf=LN(fv)` and `Lp=LN(pv)`, each stored to binary64.\n3. Form `base=D(1+rate)` and obtain the stored `Lb=LN(base)`.\n4. Store `difference=D(Lf-Lp)`, then `duration=D(difference/Lb)`. Return `#NUM!` if the result is nonfinite.\n\nFor rate `0.25`, pv `64` and fv `100`, the current x87-LN reconstruction gives these intermediate numbers:\n\n| Stage | Stored binary64 value |\n|---|---:|\n| LN(100) | 4.605170185988092 |\n| LN(64) | 4.1588830833596715 |\n| Difference | 0.4462871026284203 |\n| LN(1.25) | 0.22314355131420976 |\n| Division | 2.0000000000000036 |\n\nThe mathematical duration is exactly two; the table is a worked reconstruction of the cited operation tree, rather than an additional Excel measurement. Its split logarithms can lose low bits in the subtraction. Do not first compute `fv/pv` and take one logarithm: the source’s retained 80-input control distinguishes that ratio-log candidate from the split graph. The LN instruction approximation and transfer to other CPUs remain separately scoped.\n\n\n", "quirks": "\nThe documented arguments must all be positive; invalid values give `#NUM!`, and invalid data types give `#VALUE!`. A target below the starting amount is still permitted and gives a negative duration at a positive rate.\n\nThe current helper has no equal-value shortcut before its logarithm calculation. Equal positive amounts normally give zero, but a rate so small that stored `1+rate` equals one makes the denominator zero; the resulting nonfinite calculation gives `#NUM!`. Replacing the denominator by a stable `log1p(rate)` would change this boundary behaviour.\n\n\n", "sources": "\n- [Microsoft: PDURATION function](https://support.microsoft.com/en-us/excel/functions/pduration-function), opened 6 November 2026; syntax, documented argument rules and errors.\n- [DnaCalc implementation](https://github.com/DnaCalc/DnaCalc/blob/da3ecc4fb19a3a5529708c311d0e8f05688ac165/crates/calc-func/src/ported/financial_time_value_family.rs); implementation steps and the limits identified in the text.\n\n", "try-it": "\n`=PDURATION(0.25,64,100)` is about `2`: `64*1.25^2=100`. The result can be fractional; a target below the starting value gives a negative mathematical duration at a positive rate.\n\n\n", "version-differences": "The recorded environments below distinguish a reading from a same-input comparison. Counts describe captured inputs in each environment; overlapping captures and comparisons are not totals of unique worksheet calls.\n\n| Excel 16.0 build | Platform and CPU | Captured inputs |\n|---|---|---:|\n| 20430 | Windows, 64-bit, CPU not recorded | 1,205 |\n\nThe record contains no same-input comparison between these environments. Reading different inputs on different builds does not establish either a version change or cross-build agreement.\n\n[Recorded environments and comparison details](https://github.com/DnaCalc/ExcelFunctionsHandbook/blob/5dc75391aa5125ccc5abdb095da85950980d6fd8/content/evidence/environments/FUNC.PDURATION.json).", "what-it-does": "\n`PDURATION(rate,pv,fv)` returns the number of periods for a positive amount to grow to a positive target at a positive constant rate, without intervening payments.\n\n\n" }, "signature": { "display": "PDURATION(rate, pv, fv)", "parameters": [ { "description": null, "name": "rate", "optional": false, "repeats": false }, { "description": null, "name": "pv", "optional": false, "repeats": false }, { "description": null, "name": "fv", "optional": false, "repeats": false } ], "trailing_repeats": false }, "sources": { "metadata": { "admission": { "label": "implemented", "reason": null }, "arity": { "max": 3, "min": 3 }, "category": "Financial functions", "classification": { "arg_preparation_profile": "RefsVisibleInAdapter", "coercion_lift_profile": "Custom", "determinism_class": "Deterministic", "error_collapse_profile": "None", "fec_dependency_profile": "None", "host_interaction_class": "None", "kernel_signature_class": "Custom", "rich_value_usage": "RichBlind", "surface_fec_dependency_profile": "RefOnly", "thread_safety_class": "SafePure", "volatility_class": "NonVolatile" }, "descriptions": { "long": null, "short": "Number of periods an investment needs to grow to a target value at a fixed rate", "short_source": "dna-calc-own" }, "docs": { "english_description": "Returns the number of periods required by an investment to reach a specified value", "microsoft_url": "https://support.microsoft.com/en-us/office/pduration-function-44f33460-5be5-4c90-b857-22308892adaf" }, "entry_kind": "built_in_function", "localized_family_names": null, "localized_names": [ { "locale": "ar-SA", "name": "PDURATION" }, { "locale": "bg-BG", "name": "PDURATION" }, { "locale": "cs-CZ", "name": "PDURATION" }, { "locale": "da-DK", "name": "PVARIGHED" }, { "locale": "de-DE", "name": "PDURATION" }, { "locale": "el-GR", "name": "PDURATION" }, { "locale": "en-AU", "name": "PDURATION" }, { "locale": "en-GB", "name": "PDURATION" }, { "locale": "en-US", "name": "PDURATION" }, { "locale": "es-ES", "name": "P.DURACION" }, { "locale": "et-EE", "name": "PDURATION" }, { "locale": "fi-FI", "name": "KESTO.JAKSO" }, { "locale": "fr-FR", "name": "PDUREE*" }, { "locale": "he-IL", "name": "PDURATION" }, { "locale": "hr-HR", "name": "PDURATION" }, { "locale": "hu-HU", "name": "KAMATÉRZ.PER" }, { "locale": "id-ID", "name": "PDURATION" }, { "locale": "it-IT", "name": "PDURATION" }, { "locale": "ja-JP", "name": "PDURATION" }, { "locale": "ko-KR", "name": "PDURATION" }, { "locale": "lt-LT", "name": "PDURATION" }, { "locale": "lv-LV", "name": "PDURATION" }, { "locale": "nb-NO", "name": "PVARIGHET" }, { "locale": "nl-NL", "name": "PDUUR" }, { "locale": "pl-PL", "name": "O.CZAS.TRWANIA" }, { "locale": "pt-BR", "name": "PDURATION" }, { "locale": "pt-PT", "name": "PDURAÇÃO" }, { "locale": "ro-RO", "name": "PDURATION" }, { "locale": "ru-RU", "name": "ПДЛИТ" }, { "locale": "sk-SK", "name": "PDURATION" }, { "locale": "sl-SI", "name": "PDURATION" }, { "locale": "sr-Latn-RS", "name": "PDURATION" }, { "locale": "sv-SE", "name": "PLÖPTID" }, { "locale": "th-TH", "name": "PDURATION" }, { "locale": "tr-TR", "name": "PSÜRE" }, { "locale": "uk-UA", "name": "PDURATION" }, { "locale": "vi-VN", "name": "PDURATION" }, { "locale": "zh-CN", "name": "PDURATION" }, { "locale": "zh-HK", "name": "PDURATION" }, { "locale": "zh-TW", "name": "PDURATION" } ], "signature": { "display": "PDURATION(rate, pv, fv)", "parameters": [ { "description": null, "name": "rate", "optional": false, "repeats": false }, { "description": null, "name": "pv", "optional": false, "repeats": false }, { "description": null, "name": "fv", "optional": false, "repeats": false } ], "trailing_repeats": false }, "surface_name": "PDURATION", "version_marker": null, "xlcall": { "code": "570", "symbol": "xlfPduration" } }, "microsoft": "https://support.microsoft.com/en-us/office/pduration-function-44f33460-5be5-4c90-b857-22308892adaf" }, "try_it": { "formula": "=PDURATION(0.25,64,100)" }, "url": "https://handbook.dnacalc.com/functions/PDURATION.html", "variants": [], "versions": [ { "behaviour": "1,205 captured inputs are indexed for this environment. Capture dates: 2026-09-29 to 2026-09-29. This is a reading count, not a comparison with another build.", "excel_build": "16.0 build 20430", "platform": "Windows, 64-bit, CPU not recorded", "sources": [ "https://github.com/DnaCalc/ExcelFunctionsHandbook/blob/5dc75391aa5125ccc5abdb095da85950980d6fd8/content/evidence/environments/FUNC.PDURATION.json" ] } ] }