401(k) to Roth IRA Conversion Calculator

A conversion generally moves pre-tax retirement money into a Roth account and includes the converted amount in taxable income for the year. The calculator estimates that cost by adding your current federal tax bracket and state tax rate. It then compares the Roth projection with a traditional account projection reduced by the assumed retirement tax rate.

For the default inputs, the calculator uses a $200,000 balance, age 45, retirement at 65, a 24% current federal bracket, a 22% retirement federal bracket, 5% state tax, a 7% annual return, and a one-year conversion. It assumes you pay conversion taxes from outside the 401(k).

Its default results are $58,000 Tax Cost Now, $773,937 Roth at Retirement, -$15,479 Net Benefit, and no break-even age found. The negative net benefit means that, under these assumptions, the modeled after-tax traditional balance is larger at age 65. It is not a prediction of future tax law or market returns.

Enter the pre-tax 401(k) balance you plan to convert, your current age, and your intended retirement age. The difference between the ages sets the years available for investment growth. If you plan to convert in stages, enter the number of years over which to spread the conversion.

The current federal tax bracket and state tax rate estimate the tax due on the conversion. The retirement tax bracket estimates the tax rate applied to a traditional account withdrawal in retirement. These are simplified rates: the calculator adds the entered percentages rather than calculating your complete federal and state returns.

Set expected investment return to the same assumption for both account paths. Choose whether conversion taxes come from outside funds. Paying externally preserves more of the converted balance inside the Roth, but the outside money also has an opportunity cost: it could otherwise have been invested. Compare Roth outcomes with the Roth IRA Calculator and model later distributions with the Roth IRA Withdrawal Calculator.

The calculator adds the 24% current federal bracket and 5% state rate to estimate a 29% conversion tax rate:

• $200,000 × (24% + 5%) = $58,000 estimated tax cost now.
• $200,000 × 1.07^20 = $773,937 projected Roth balance before subtracting the outside-tax opportunity cost.
• $58,000 × 1.07^20 = $224,442 estimated future value of the outside money used to pay the tax.
• $773,937 − $224,442 = $549,495 Roth value net of that modeled cost.
• $200,000 × 1.07^20 = $773,937 projected traditional balance before tax.
• $773,937 × (1 − 27%) = $564,974 estimated traditional balance after the assumed 22% federal and 5% state retirement rates.
• $549,495 − $564,974 = −$15,479 net benefit for the Roth path at age 65.

The calculator reports a break-even age of 0 when the modeled Roth value never reaches the modeled traditional after-tax value by age 100. In this example, it does not find a crossover. That output means “no break-even found in the modeled range,” not that a person’s age is zero.

A 401(k)-to-Roth IRA rollover is not always available in the same way for every worker. Eligibility and options depend on plan rules and circumstances such as leaving an employer or qualifying for an in-service distribution. Ask the plan administrator which rollover choices apply. The IRS explains rollovers of retirement plan and IRA distributions.

A conversion of pre-tax money is generally taxable in the year converted. A direct rollover can move funds between custodians without treating the money as paid to you, but converting pre-tax assets to Roth treatment generally creates taxable income. A rollover involving after-tax basis can have different tax treatment; the calculator assumes the full entered balance is pre-tax.

The calculator does not determine your exact marginal tax rate, deductions, credits, Medicare premiums, or state-specific treatment. A conversion can push income into a higher federal bracket or affect income-based thresholds. The IRS describes how federal income tax brackets work. Do not assume the calculator’s combined rate is your final tax liability.

The result also depends heavily on how the conversion tax is paid. If you pay it from the retirement account rather than outside funds, less money may remain invested in the Roth, and an under-59½ distribution of withheld funds may have additional tax consequences. Compare the account-growth assumptions with a Roth 401(k) Calculator or a Roth IRA Tax Calculator.

Estimated conversion tax rate = (current federal tax bracket + state tax rate) / 100

Tax cost now = 401(k) balance × estimated conversion tax rate

Traditional after-tax value = 401(k) balance × (1 + annual return)^years × (1 − retirement tax rate)

Net benefit = Roth value after outside-tax cost − traditional after-tax value

For the default example, annual return is 7%, the conversion tax rate is 29%, and the retirement tax rate is 27%. The calculator grows the balance using annual compounding. Its staged-conversion logic and outside-tax opportunity-cost estimate are simplified projections, not a year-by-year tax-return calculation.

Change one assumption at a time to see what drives the result. The figures below illustrate the direct effect of the tax-rate assumptions on a $200,000 balance; they are not calculator result cards.

A lower current tax rate makes conversion less expensive upfront. A lower retirement tax rate can favor leaving money in a traditional account. But future income, tax law, account withdrawals, and investment returns can change the comparison. For related planning, see Roth IRA vs. traditional IRA: which saves more taxes? and the Roth conversion ladder guide.

Does converting a 401(k) to a Roth IRA always create a tax bill?

Converting pre-tax money generally creates taxable income for the conversion year. The amount and reporting depend on the funds’ tax character and how the rollover is completed. See the IRS rollover guidance and confirm your plan’s distribution options.

Is a direct rollover the same as a Roth conversion?

No. A direct rollover describes how funds move between accounts; a Roth conversion describes changing pre-tax retirement money to Roth tax treatment. A direct rollover to a traditional IRA may defer tax, while a conversion to a Roth account generally recognizes taxable income on pre-tax funds.

Should I convert all at once or spread conversions over several years?

Spreading conversions may help manage taxable income in each year, but it can also keep some funds invested in the traditional account longer. Compare an amount that fits your available tax bracket with a larger one-time conversion, and include other income in the analysis. This calculator models the conversion period simply; it does not calculate annual tax brackets separately.

Does a negative net benefit prove a Roth conversion is a bad idea?

No. It means the Roth projection is lower under the entered assumptions at the selected retirement age. The calculator cannot forecast future tax law, withdrawals, estate outcomes, or your actual tax rates. Test different current and retirement tax rates before drawing a conclusion.

Why does break-even age show 0?

The calculator uses 0 when it finds no age from the year after your current age through age 100 at which the modeled Roth value reaches the traditional after-tax value. It is a “not found” signal, not a literal break-even age.

Can I use money from my 401(k) to pay the tax?

You can have funds withheld from a distribution in some situations, but less money then reaches the Roth account, and an early distribution may have additional tax consequences. Paying tax from outside funds preserves the conversion amount in the Roth, but those outside funds have an investment opportunity cost.

First, confirm whether your plan permits the rollover and whether the balance is entirely pre-tax. Then estimate how the conversion would affect taxable income in the conversion year, including other income and deductions. Test multiple conversion amounts and compare assumptions rather than relying on one forecast.

For related planning, estimate 401(k) growth with the 401(k) Calculator, compare contribution choices with the 401(k) Contribution Calculator, and evaluate distributions using the Roth 401(k) Withdrawal Calculator. For required minimum distribution planning, see how to calculate your RMD step by step.