Roth 401(k) Calculator

Before you enter your numbers

Enter annual employee and employer contributions separately. Traditional and Roth employee deferrals share the applicable employee limit rather than each having a separate allowance. If you contribute to both, enter only the amount allocated to this modeled balance.

• Current Roth 401(k) balance
• Monthly contribution
• Years to retirement
• Expected annual return

Input reference

• Current Roth 401(k) balance: The current balance committed to this goal. Use a recent statement and exclude money reserved for unrelated goals. This starting value is already invested, so do not also enter it as a recurring contribution.
• Current age: Your age at the start of the projection. This determines how long contributions can compound before the selected retirement date; it does not set legal access to a pension or retirement account.
• Annual employee contribution: New employee or IRA saving each year, spread into monthly deposits in the model. This is distinct from the existing balance, rollovers and separately entered employer funding. Statutory caps may limit the modeled contribution.
• Annual employer contribution: Annual employer money expected to remain in the account. It is modeled separately from employee contributions. Confirm vesting and the plan’s formula before assuming the full amount will be retained.
• Years to retirement: The duration of the calculation in years. Longer periods give growth or withdrawals more time to operate. This is a chosen modeling horizon, not a prediction of an investment term or your lifetime.
• Annual return: An assumed nominal annual rate, divided by 12 in monthly projections. It is held constant. It is not a guaranteed yield, and the default should be replaced with an assumption suited to your scenario.

Formula and calculation method

The tool caps employee contributions using the 2026 limit for the entered current age and holds that annual amount constant across the projection. Employer contributions are added separately and divided into monthly deposits. It does not automatically increase the cap when you reach a later catch-up age.

Worked example

With 10,000 already saved, 6,000 of annual employee contributions and no employer contribution, a 10-year zero-return scenario ends at 70,000. Changing the account label from traditional to Roth does not change this gross balance; it changes the tax questions attached to the money.

How to interpret the result

The result panel reports projected Roth 401(k) balance, total contributions and estimated investment growth.

Do not automatically describe the entire projected balance as tax-free. Employer contributions may be held in a different tax source depending on the plan and election. The model also excludes contribution eligibility, qualified-distribution tests, payroll tax effects and the combined plan ceiling.

Contribution limits and Roth treatment

The projection caps employee contributions at the 2026 401(k) elective-deferral limit that applies to the entered age, while employer contributions are modeled separately. Roth 401(k) contributions are generally made after tax, so the calculator focuses on account growth rather than deducting a current-year tax benefit.

Employer contributions can have different tax treatment depending on plan design and current law. The calculator therefore shows growth, not an individualized after-tax retirement value.

Compare accounts on an equal-cost basis

An equal-dollar contribution comparison can be misleading when one contribution reduces current taxable income and the other does not. Compare the effect on take-home pay and consider how any current tax savings would be used. This calculator does not invest or spend those tax savings on your behalf.

Keep Roth and non-Roth sources identifiable in your statements. Combining them into one balance is acceptable for rough investment growth, but it cannot establish the amount available tax-free. Before using a withdrawal estimate, verify the conditions and tax treatment that apply to each source.

Keep contribution growth separate from tax treatment

The projection shows account growth; it does not decide whether Roth or traditional contributions are better for you. That choice depends on current and future tax rates, plan features, employer contributions and withdrawal rules. A future balance can be identical under the same contributions and investment returns even though the tax treatment differs.

Use the result as the investment-growth side of the decision. For a tax comparison, calculate the cash flow available to contribute under each option and compare after-tax retirement withdrawals rather than comparing two pre-tax contribution amounts that do not represent the same household cost.

Use The Result In The Next Calculation

Compare the projected Roth 401(k) balance with the traditional 401(k) projection only after keeping contributions, employer match and return assumptions consistent. Tax treatment is different from account growth, so use current tax rules separately from the projection.