401(k) to Roth IRA Conversion Calculator

Determine the tax cost and long-term financial benefit of converting a traditional 401(k) to a Roth IRA. This calculator compares two scenarios: converting now and paying taxes, versus keeping your 401(k) and paying taxes on withdrawals in retirement. It helps you answer the critical question: will you have more after-tax money by converting?

This tool is for anyone with a traditional, pre-tax 401(k) who is considering a Roth conversion to achieve tax diversification and tax-free growth. Whether you're planning for retirement, in a low-income year, or simply want to compare your options, this calculator provides a data-driven starting point. For a broader look at retirement accounts, see our main Roth IRA Calculator or the general 401(k) Calculator. Learn the fundamental differences in our guide to Roth vs. Traditional IRAs.

The results provide a clear "Conversion Benefit" score, the immediate tax cost, your projected Roth balance at retirement, the total net benefit of converting, and a break-even age. A detailed chart visualizes the after-tax value of each option over time, helping you see when the conversion pays off.

Begin with the "Conversion Details" section. Enter the 401(k) Balance to Convert, which is the pre-tax amount you are considering moving. Next, input your Current Age and planned Retirement Age. This time horizon is a critical factor, as it determines how many years your converted funds have to grow tax-free.

Move to the "Tax Rates & Returns" section. Enter your Current Federal Tax Bracket and your best estimate for your Expected Retirement Tax Bracket. The difference between these two rates is the primary driver of a conversion's value. Then, add your Expected Annual Return, which is the average investment growth rate you anticipate for your portfolio.

For a more precise analysis, open the advanced settings. Here you can add your State Tax Rate to get a more accurate picture of the total tax cost. The Spread Conversion Over input lets you model a multi-year strategy, such as a Roth conversion ladder, which can help manage the tax impact. Finally, indicate whether you plan to Pay Taxes From External Funds. Using non-retirement money to pay the conversion tax is highly recommended and will significantly improve the outcome.

401(k) Balance to Convert

This is the total pre-tax amount from your traditional 401(k) or similar employer-sponsored plan that you intend to roll over into a Roth IRA. This entire amount will be treated as ordinary income in the year(s) you convert, which is why it's crucial to calculate the tax impact beforehand.

Current Age & Retirement Age

Your age and planned retirement age set the timeline for the calculation. A longer time horizon between your current age and retirement age gives the money in the Roth IRA more time to grow tax-free. This extended period of compounding can help overcome the initial tax cost of the conversion.

Current & Expected Retirement Tax Brackets

This is the core of the conversion decision. A Roth conversion is generally most advantageous if you expect to be in a higher tax bracket in retirement than you are today. By converting now, you pay taxes at your current, lower marginal rate and avoid paying taxes at a potentially higher future rate on a larger balance. If you're unsure of your future bracket, our retirement tax calculator can help you estimate.

Expected Annual Return

This is your estimated average annual growth rate for your investments. This rate is applied to both the Roth IRA and the traditional 401(k) balances to project their future values. A higher return magnifies the long-term benefit of the Roth's tax-free growth. A long-term market average is often estimated between 6-8%.

State Tax Rate

Your state income tax rate is added to your federal tax bracket to determine the total tax due on the conversion. Forgetting to account for state taxes is a common mistake that can lead to an unexpectedly large tax bill. If you plan to retire in a different state, consider how that might affect your decision. See our list of the best states to retire for taxes.

Spread Conversion Over

Instead of converting a large balance in a single year and potentially pushing yourself into a much higher tax bracket, you can spread the conversion over several years. For example, converting $200,000 over four years means adding $50,000 to your taxable income each year. This strategy can significantly reduce the total tax paid. This is the basic principle behind a Roth conversion ladder.

Pay Taxes From External Funds

This input asks if you will pay the conversion tax bill with money from a non-retirement account (like a checking or brokerage account) or from the 401(k) funds being converted. Paying with external funds is far more effective because it allows 100% of your converted balance to start growing in the Roth IRA. If you pay taxes from the conversion amount, you are effectively reducing your retirement savings.

The calculator runs a side-by-side projection to compare the long-term, after-tax value of converting your 401(k) to a Roth IRA versus keeping it as a traditional, pre-tax account.

Roth Conversion Path: First, it calculates the immediate tax cost by multiplying the 401(k) Balance to Convert by your combined federal and state Current Tax Bracket. If you choose to pay taxes from the conversion amount, this tax cost is subtracted from the balance. It then projects the growth of this new Roth IRA balance using your Expected Annual Return until your Retirement Age. The final projected balance represents your tax-free retirement income from this account.

Keep Traditional Path: The calculator projects the growth of your full, pre-tax 401(k) Balance to Convert using the same Expected Annual Return until Retirement Age. It then applies your Expected Retirement Tax Bracket (both federal and state) to this larger, pre-tax balance to determine its after-tax value.

The Net Benefit is the difference between the final after-tax value of the Roth IRA and the after-tax value of the traditional 401(k). The Break-Even Age is the point at which the growing, tax-free Roth balance overtakes the after-tax value of the traditional account, making the conversion profitable.

The calculator uses the following logic to project and compare the two scenarios.

Tax Calculations

Total Current Tax Rate = (Current Federal Tax Bracket + State Tax Rate) / 100

Total Retirement Tax Rate = (Expected Retirement Tax Bracket + State Tax Rate) / 100

Tax Cost Now = 401(k) Balance to Convert * Total Current Tax Rate

Roth Conversion Path Formula

This formula determines the starting balance for the Roth IRA and projects its future value.

// If paying taxes from external funds (value = 1)
Roth Start Balance = 401(k) Balance to Convert

// If paying taxes from the conversion itself (value = 0)
Roth Start Balance = 401(k) Balance to Convert - Tax Cost Now

Years to Retirement = Retirement Age - Current Age

Projected Roth Balance = Roth Start Balance * (1 + Expected Annual Return)^Years to Retirement

Keep Traditional 401(k) Path Formula

This path projects the growth of the pre-tax balance and then calculates its after-tax worth in retirement.

Projected Traditional Balance = 401(k) Balance to Convert * (1 + Expected Annual Return)^Years to Retirement

Traditional After-Tax Income = Projected Traditional Balance * (1 - Total Retirement Tax Rate)

Key Result Formulas

The final outputs are derived from comparing the two paths.

Net Benefit = Projected Roth Balance - Traditional After-Tax Income

The Break-Even Age is found by solving for the age where the value of the Roth path equals the after-tax value of the Traditional path.

A Roth conversion is a tax-planning strategy, not an investment strategy. The decision hinges almost entirely on your current and expected future income tax rates. Here are the most common scenarios where a conversion is beneficial:

1. You Expect Higher Taxes in Retirement: If you believe your income, and therefore your tax bracket, will be higher in retirement, converting now locks in today's lower rate. This is common for young professionals with high savings rates or those who expect significant pension or other income in retirement.

2. You Are in a Low-Income Year: A temporary dip in income—due to a job change, sabbatical, or starting a business—creates a perfect window to convert. You can realize the "income" from the conversion while staying in a lower-than-usual tax bracket.

3. You Want to Minimize RMDs: Traditional 401(k)s and IRAs are subject to Required Minimum Distributions (RMDs) starting at age 73 (or 75, depending on your birth year). Roth IRAs have no RMDs for the original owner. Converting can reduce your future RMDs, lowering your taxable income in retirement and giving your money more time to grow. Use our RMD calculator to see your potential future distributions.

4. You Want to Maximize Your Estate: If you plan to leave retirement funds to heirs, a Roth IRA is often a superior vehicle. Your beneficiaries can inherit the account and enjoy tax-free withdrawals, whereas inheriting a traditional IRA means they will have to pay income taxes on distributions.

5. You Believe Tax Rates Will Rise: Even if your personal income stays the same, if you believe federal or state income tax rates will increase in the future, converting now allows you to pay taxes at today's known rates.

The Roth conversion ladder is a popular strategy for those planning to retire early. It involves converting a portion of a traditional 401(k) or IRA to a Roth IRA each year for several years.

The primary goal is to create a source of tax-free and penalty-free income before age 59.5. Here's how it works:

1. Convert Annually: You convert a specific amount from your traditional account to a Roth IRA each year. You pay income tax on each conversion.
2. Wait Five Years: Each conversion amount has its own five-year waiting period. This is a crucial IRS rule.
3. Withdraw Contributions: After the five-year period for a specific conversion has passed, you can withdraw that converted amount (the principal or "contribution") tax-free and penalty-free, regardless of your age.

By "laddering" conversions over multiple years, you create a rolling pipeline of funds that become accessible five years later. This allows an early retiree to fund their living expenses before they can access other retirement accounts without penalty. For a more detailed guide, read our article on the Roth conversion ladder.

Conversion Benefit Score: This score (1-99) provides a quick summary. A high score (80+) suggests the conversion is highly beneficial based on your inputs. A moderate score (50-79) means it could be a good move, but the benefits aren't overwhelming. A low score (<50) indicates that keeping the traditional 401(k) may be the better financial choice.

Tax Cost Now: This is the estimated total income tax (federal and state) you will owe on the conversion. This is the upfront price you pay for future tax-free growth and withdrawals.

Projected Roth Balance: This is the estimated value of your converted funds at your planned retirement age, assuming your expected annual return. This entire amount is available for tax-free withdrawal in retirement.

Net Benefit: This is the bottom-line result. It shows how much more (or less) after-tax money you would have in retirement by converting. A positive number represents the financial gain from the conversion.

Break-Even Age: This is the age at which the financial benefit of the tax-free growth in the Roth IRA surpasses the initial tax cost. Living past this age means the conversion was a net positive financial decision.

Roth vs. Traditional Chart: This visual tool shows the after-tax value of both accounts over time. The "Roth" line starts lower due to the initial tax payment (if paid from the conversion) but grows to overtake the "Traditional (After-Tax)" line at the break-even point.

If the calculator shows a marginal or negative benefit, consider these strategies to improve the outcome:

• Convert in a Low-Income Year: The single biggest factor is your current tax rate. If possible, execute the conversion in a year when your taxable income is lower than usual.
• Spread the Conversion: Use the "Spread Conversion Over" input to model a multi-year strategy. Converting smaller amounts annually can prevent you from being pushed into a higher tax bracket.
• Pay Taxes From External Funds: This is critical. Using cash from a savings or brokerage account to pay the tax bill keeps your retirement savings fully intact and working for you. The calculator will show a dramatically better result when this option is selected.
• Time Your Relocation: If you plan to move from a high-tax state to a no-tax state (or vice-versa), timing your conversion can save a significant amount. Converting after you've established residency in the lower-tax state can be a powerful move.

1. Underestimating the Tax Bill: The converted amount is added to your ordinary income, which can push you into a higher tax bracket and phase you out of certain deductions and credits.
2. Forgetting State Taxes: Many people focus only on federal brackets, but state income tax can add a significant cost to the conversion.
3. Paying Taxes From the Conversion: Withdrawing funds from the converted amount to pay the tax bill reduces the principal that can grow tax-free, diminishing the long-term benefit. If you are under 59.5, that withdrawal may also be subject to a 10% early withdrawal penalty.
4. Ignoring the Impact on Medicare Premiums: A large conversion increases your Modified Adjusted Gross Income (MAGI). This can trigger higher Medicare Part B and Part D premiums two years later due to the Income-Related Monthly Adjustment Amount (IRMAA).
5. Missing the 5-Year Rule: Each conversion has its own 5-year clock. If you withdraw earnings from a Roth IRA before age 59.5 AND before the 5-year period is up, those earnings can be subject to taxes and penalties.