Fidamen

401(k) Calculator

This calculator projects the future value of a 401(k) using your current balance, regular contributions, employer match, and an expected annual return. It supports multiple planning modes: a standard projection, a target-income planner, and an early-withdrawal impact estimator.

Results are model-based estimates to help with planning and do not guarantee investment performance. Use conservative assumptions and consult a licensed financial or tax professional for personalized advice.

Updated Nov 18, 2025QA PASS — golden 25 / edge 120Run golden-edge-2026-01-23

Governance

Record 18b38c6925ef • Reviewed by Fidamen Standards Committee

Project account balance at retirement using periodic contributions, employer match, compounding returns and inflation adjustment.

Inputs

Advanced inputs

Standard projection inputs

Target-income planner inputs

Early withdrawal inputs

Results

Updates as you type

Projected balance at retirement

$1,317,845.64

Estimated first-year withdrawable income (nominal)

$52,713.83

Inflation-adjusted withdrawable income (today's dollars)

$25,130.93

OutputValueUnit
Projected balance at retirement$1,317,845.64USD
Estimated first-year withdrawable income (nominal)$52,713.83USD
Inflation-adjusted withdrawable income (today's dollars)$25,130.93USD
Primary result$1,317,845.64

Visualization

Methodology

We compound contributions at a periodic rate derived from the annual expected return and the chosen contribution frequency. Employer match is estimated as an annual percent of salary and added on each contribution period.

The tool uses standard future value formulas for lump sums and annuities. For withdrawal estimates it multiplies the projected balance by a user-selected withdrawal rate to estimate first-year income. Early-withdrawal estimates calculate likely tax and penalty amounts using user-provided tax and penalty rates.

Key takeaways

This advanced calculator supports multiple planning modes and helps estimate projected 401(k) balances, required savings for target income, and the cost of early withdrawals.

Inputs should reflect your best current estimates. Results are modeling outputs, not guarantees. Always verify plan-specific rules (employer match formula, contribution limits) and consult professionals for legal, tax, or investment decisions.

Worked examples

Example: Age 35, $25,000 balance, $10,000 annual contribution, 6.5% return, retire at 65 → projected balance is the sum of compounded current balance plus compounded future contributions (including employer match).

Target-income example: If you want $40,000/year and use a 4% withdrawal rate, required balance = $40,000 / 0.04 = $1,000,000. The tool compares that to your projected balance.

F.A.Q.

Is this a substitute for professional financial or tax advice?

No. This calculator provides estimates only and is not tailored financial or tax advice. Consult a qualified advisor for decisions impacting your retirement and taxes.

How should I choose the expected return and inflation assumptions?

Use long-term, realistic assumptions based on diversified portfolio expectations. Consider using conservative assumptions for planning. Historical returns are not predictive of future returns.

Does this tool account for taxes on withdrawals?

You can provide an estimated marginal tax rate for early withdrawal scenarios. The standard projection does not model future taxes on distributions; adjust assumptions or consult a tax advisor to estimate post-tax income.

How are employer matches treated?

Employer match is estimated as a percent of salary and prorated per contribution period. If your plan uses a different formula (e.g., dollar-for-dollar up to a percent of your contribution), adjust the employer match fields to approximate the actual policy.

Sources & citations

Further resources

Versioning & Change Control

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

Record ID: 18b38c6925ef

What changed (latest)

v1.0.0 • 2025-11-18 • 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 18, 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 • 2025-11-18 • 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: c5ece7b363ab