Fidamen

Retirement Withdrawal Calculator

This calculator compares multiple withdrawal approaches so you can estimate how long retirement savings may last under different assumptions. It includes a fixed-percentage approach (popularized as the 4% rule), a systematic inflation-adjusted withdrawal computed for a chosen planning horizon, and a simple approximation of Required Minimum Distributions (RMD).

Results are model-based estimates intended to support planning conversations. They depend on the assumptions you enter: expected returns, inflation, withdrawal choices, and life-horizon. Use conservative assumptions and consult a financial professional for personalized advice.

Updated Nov 7, 2025QA PASS — golden 25 / edge 120Run golden-edge-2026-01-23

Governance

Record 745c2cc861c7 • Reviewed by Fidamen Standards Committee

Estimates years until portfolio depletion assuming a constant initial withdrawal rate that is thereafter adjusted for inflation. Uses an analytic annuity depletion formula on an inflation-adjusted (real) basis.

Inputs

Advanced inputs

Pension & Social Security

Results

Updates as you type

Initial annual withdrawal

$20,000.00

Estimated years before depletion

—

OutputValueUnit
Initial annual withdrawal$20,000.00USD
Estimated years before depletion—years
Primary result$20,000.00

Visualization

Methodology

Calculations convert nominal returns to real (inflation-adjusted) returns before applying annuity or depletion formulas so withdrawal sustainability is expressed in constant purchasing power.

Fixed-percentage method: computes initial withdrawal as portfolio × withdrawal rate, then estimates years before depletion using an analytic annuity depletion formula in real terms. If real return is zero or negative, a simple exhaustion estimate (portfolio / withdrawal) is used.

Systematic (inflation-adjusted) method: derives the first-year withdrawal that can be increased by inflation each year while depleting the portfolio exactly over the chosen horizon using the real-return annuity formula.

RMD estimate: uses a simplified divisor approximation for an illustrative first-year RMD. It is not a replacement for IRS published tables or tax advice.

F.A.Q.

Is this a guaranteed forecast?

No. Outputs are estimates based on deterministic formulas and the inputs you provide. Actual investment returns, inflation, taxes, fees, and spending behavior will change outcomes. Treat results as planning scenarios, not guarantees.

How should I pick expected return and inflation?

Use conservative, literature-backed assumptions and test sensitivity. Professional guidance often recommends stress-testing lower returns and higher inflation. This tool includes fields so you can run scenarios with different assumptions.

Does this replace tax or legal advice (including RMD calculations)?

No. RMDs and tax treatments are governed by tax authorities and plan rules. This tool provides a simple approximation for planning. Consult an accountant or plan administrator for exact RMDs and tax consequences.

What are the accuracy and data-handling standards behind this tool?

This calculator follows engineering and information-quality practices: testability and reproducibility of formulas, documented assumptions, and clear caveats. For software and information security considerations, designers should follow NIST best practices for risk management, ISO standards for quality management where applicable, and IEEE guidance on software engineering quality. Workplace and compliance obligations may reference OSHA requirements for operational safety. Results remain model outputs and should be validated by qualified professionals for high-stakes decisions.

Sources & citations

Further resources

External guidance

Versioning & Change Control

Audit record (versions, QA runs, reviewer sign-off, and evidence).

Record ID: 745c2cc861c7

What changed (latest)

v1.0.0 • 2025-11-07 • MINOR

Initial publication and governance baseline.

Why: Published with reviewed formulas, unit definitions, and UX controls.

Public QA status

PASS — golden 25 + edge 120

Last run: 2026-01-23 • Run: golden-edge-2026-01-23

Engine

v1.0.0

Data

Baseline (no external datasets)

Content

v1.0.0

UI

v1.0.0

Governance

Last updated: Nov 7, 2025

Reviewed by: Fidamen Standards Committee (Review board)

Credentials: Internal QA

Risk level: low

Reviewer profile (entity)

Fidamen Standards Committee

Review board

Internal QA

Entity ID: https://fidamen.com/reviewers/fidamen-standards-committee#person

Semantic versioning

  • MAJOR: Calculation outputs can change for the same inputs (formula, rounding policy, assumptions).
  • MINOR: New features or fields that do not change existing outputs for the same inputs.
  • PATCH: Bug fixes, copy edits, or accessibility changes that do not change intended outputs except for previously incorrect cases.

Review protocol

  • Verify formulas and unit definitions against primary standards or datasets.
  • Run golden-case regression suite and edge-case suite.
  • Record reviewer sign-off with credentials and scope.
  • Document assumptions, limitations, and jurisdiction applicability.

Assumptions & limitations

  • Uses exact unit definitions from the Fidamen conversion library.
  • Internal calculations use double precision; display rounding follows the unit's configured decimal places.
  • Not a substitute for calibrated instruments in regulated contexts.
  • Jurisdiction-specific rules may require official guidance.

Change log

v1.0.0 • 2025-11-07 • MINOR

Initial publication and governance baseline.

Why: Published with reviewed formulas, unit definitions, and UX controls.

Areas: engine, content, ui • Reviewer: Fidamen Standards Committee • Entry ID: 3e07a37e368e