Fidamen

Traditional IRA Calculator

This calculator models the future balances and after-tax proceeds for Traditional and Roth IRAs under user-provided assumptions. It estimates a Traditional IRA's tax-deferred growth and the tax due at withdrawal, and compares that with a Roth IRA that grows tax-free after an initial after-tax contribution.

Use this tool to explore sensitivity to assumptions (returns, contribution amounts, and tax rates today vs retirement). Results are illustrative and use deterministic formulas; they do not represent investment advice or tax advice.

Updated Nov 26, 2025QA PASS — golden 25 / edge 120Run golden-edge-2026-01-23

Governance

Record a400227bc3b2 • Reviewed by Fidamen Standards Committee

Computes both Traditional and Roth outcomes using the same inputs and reports the net difference and percent advantage.

Inputs

Results

Updates as you type

Net after-tax proceeds (Traditional)

$369,992.31

Net after-tax proceeds (Roth)

$360,505.33

Roth minus Traditional (net difference)

-$9,486.98

Percent advantage for Roth vs Traditional

—

OutputValueUnit
Net after-tax proceeds (Traditional)$369,992.31USD
Net after-tax proceeds (Roth)$360,505.33USD
Roth minus Traditional (net difference)-$9,486.98USD
Percent advantage for Roth vs Traditional—%
Primary result$369,992.31

Visualization

Methodology

Future value uses standard compound growth and annuity formulas: future value of a lump sum plus future value of a series of level annual contributions.

Traditional IRA contributions are treated as pre-tax for the projection: the model grows the full contribution and then applies the assumed retirement marginal tax rate to withdrawals. Roth IRA projections treat contributions as after-tax and apply no tax to qualified withdrawals.

The tool assumes level (equal) annual contributions and a constant annual return compounded yearly. It does not model intra-year timing, tax brackets, required minimum distributions, state taxes, capital gains distinctions, or early-withdrawal penalties.

Key takeaways

This tool provides side-by-side projections for Traditional vs Roth IRAs using user-supplied assumptions. It is intended for educational comparisons, not as a substitute for professional advice.

For compliance and verification, consult official tax publications and a qualified tax or financial professional before making tax-sensitive decisions.

F.A.Q.

Does this calculator enforce IRS contribution limits or eligibility rules?

No. This tool does not enforce contribution limits, income phaseouts, or eligibility rules. Refer to official tax guidance for current contribution limits and eligibility. Adjust inputs to reflect legal limits for your situation.

Are state taxes, brackets, and other real-world factors included?

No. The model applies a single marginal tax rate at contribution (current_tax_rate_pct) and another at withdrawal (retirement_tax_rate_pct). It does not model progressive tax brackets, state taxes, Medicare surtaxes, or changes in tax law.

How accurate are these estimates?

Estimates use deterministic mathematical formulas based on user inputs. They should be treated as illustrative. For formal tax or financial planning, consult a qualified advisor and verify inputs against current regulatory guidance.

Sources & citations

Further resources

Versioning & Change Control

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

Record ID: a400227bc3b2

What changed (latest)

v1.0.0 • 2025-11-26 • 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 26, 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 • 2025-11-26 • 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: 7ab4bc6ad84f