A Roth conversion can be an important retirement planning strategy for people who want to move money from a traditional retirement account into a Roth account. Unlike a traditional IRA or traditional 401(k), qualified Roth withdrawals can generally be tax-free in retirement. However, converting pre-tax retirement money to a Roth account can create taxable income in the year of the conversion.
Roth Conversion Calculator
What Is a Roth Conversion?
A Roth conversion generally involves moving money from a traditional IRA or another eligible pre-tax retirement account into a Roth IRA. The converted amount may be included in taxable income for the year of the conversion.
For example, suppose you have $100,000 in a traditional IRA and decide to convert $20,000 to a Roth IRA. If the entire $20,000 is taxable and you use an assumed marginal tax rate of 24%, a simplified estimate of the federal tax attributable to the conversion would be:
$20,000 × 24% = $4,800
The actual amount of tax you owe can differ because a conversion can interact with your other taxable income and tax brackets.
The potential attraction of the conversion is that money moved into a Roth account can potentially grow for years and, when applicable requirements are met, qualified withdrawals can be tax-free.
What the Roth Conversion Calculator Calculates
This calculator provides six primary results:
- Estimated Conversion Tax
- After-Tax Conversion Amount
- Future Roth Value
- Future Value of Tax Cost
- Estimated Net Future Value
- Estimated Taxable Income After Conversion
These figures provide a simplified way to examine the immediate and projected financial effects of a Roth conversion.
How to Use the Roth Conversion Calculator
Using the calculator requires six inputs.
1. Traditional IRA / 401(k) Balance
Enter the current balance of the traditional retirement account you are considering for conversion.
For example:
$150,000
The calculator uses this amount to make sure that the conversion amount does not exceed the account balance.
2. Other Taxable Income
Enter your estimated taxable income from other sources for the year.
For example:
$60,000
This is important because a Roth conversion can increase taxable income.
3. Amount to Convert to Roth
Enter the amount you are considering converting.
For example:
$25,000
The calculator requires the conversion amount to be greater than zero and no greater than the retirement account balance.
4. Estimated Marginal Tax Rate
Enter the marginal tax rate you want to use for the estimate.
For example:
24%
This calculator uses the rate as a simplified assumption rather than calculating a complete progressive federal tax return.
5. Expected Annual Investment Return
Enter your expected annual investment return.
The calculator defaults to:
7%
You can change this assumption based on the return you want to model.
Remember that investment returns are uncertain. A projected 7% annual return does not guarantee that the account will actually earn 7% every year.
6. Years Until Withdrawal
Enter the number of years you expect the money to remain invested before withdrawal.
For example:
20 years
A longer investment period can have a substantial effect on the projected future value because of compound growth.
After entering the information, select Calculate to see the estimates.
Roth Conversion Formula Explained
The calculator uses several straightforward mathematical formulas.
1. Estimated Conversion Tax
The first calculation estimates the tax associated with the conversion:
Conversion Tax = Conversion Amount × Tax Rate
For example:
- Conversion amount = $25,000
- Tax rate = 24%
Therefore:
$25,000 × 0.24 = $6,000
The estimated conversion tax is $6,000.
This is a simplified estimate and should not be interpreted as the exact additional tax shown on your tax return.
2. After-Tax Conversion Amount
The calculator displays the entire conversion amount as the amount placed into the Roth projection:
After-Tax Conversion Amount = Conversion Amount
This is an important assumption in the calculator.
The tax is modeled separately rather than subtracting the tax from the Roth account balance. In other words, the calculation assumes that the estimated tax is paid from funds outside the converted retirement account.
This distinction matters because paying conversion taxes from the retirement account itself could reduce the amount that remains invested.
3. Future Roth Value
The calculator estimates the future value of the converted amount using compound growth:
Future Roth Value = Conversion Amount × (1 + Annual Return)^Years
Suppose you convert $25,000, expect a 7% annual return, and leave it invested for 20 years:
Future Roth Value = $25,000 × (1.07)^20
The resulting value is approximately $96,742.
This is a mathematical projection, not a guaranteed investment result.
4. Future Value of the Tax Cost
The calculator also calculates what the estimated tax cost could grow to if the tax amount were invested instead:
Future Tax Cost = Conversion Tax × (1 + Annual Return)^Years
Using the previous example:
- Conversion tax = $6,000
- Annual return = 7%
- Time = 20 years
The projected future value is approximately:
$23,218
This calculation provides an opportunity-cost comparison. Paying taxes today means those dollars are no longer available for another investment unless you have additional funds to cover the tax.
5. Estimated Net Future Value
The calculator subtracts the projected future value of the tax cost from the projected future Roth value:
Net Future Value = Future Roth Value − Future Tax Cost
Using the example:
$96,742 − $23,218 = approximately $73,524
This figure should be viewed as a simplified comparison rather than a complete retirement-tax projection.
6. Estimated Taxable Income After Conversion
The calculator adds the conversion amount to the other taxable income:
Taxable Income After Conversion = Other Taxable Income + Conversion Amount
For example:
- Other taxable income = $60,000
- Roth conversion = $25,000
Therefore:
$60,000 + $25,000 = $85,000
The calculator displays $85,000 as the estimated taxable income after the conversion.
Actual taxable income calculations can be more complicated because deductions, exemptions, other income sources, capital gains, and other tax rules can affect the final result.
Roth Conversion Calculator Example
Consider someone with the following assumptions:
| Input | Example |
|---|---|
| Traditional IRA / 401(k) Balance | $150,000 |
| Other Taxable Income | $60,000 |
| Roth Conversion Amount | $25,000 |
| Estimated Marginal Tax Rate | 24% |
| Expected Annual Return | 7% |
| Years Until Withdrawal | 20 |
Step 1: Calculate the conversion tax
$25,000 × 24% = $6,000
The estimated conversion tax is $6,000.
Step 2: Project the Roth balance
The $25,000 conversion is projected at a 7% annual return for 20 years.
$25,000 × (1.07)^20 ≈ $96,742
Step 3: Project the tax opportunity cost
If the $6,000 tax cost were invested at the same 7% return for 20 years:
$6,000 × (1.07)^20 ≈ $23,218
Step 4: Estimate net future value
$96,742 − $23,218 ≈ $73,524
Step 5: Estimate taxable income after conversion
$60,000 + $25,000 = $85,000
This example illustrates how the calculator connects the immediate tax cost with long-term compound growth.
Roth Conversion and Compound Growth
One of the major reasons investors consider Roth conversions is the potential for long-term tax-free growth on qualified Roth assets.
Compound growth means that investment returns can themselves generate additional returns over time.
For example, a $25,000 investment growing at 7% annually would approximately become:
| Years | Approximate Value |
|---|---|
| 0 | $25,000 |
| 5 | $35,064 |
| 10 | $49,179 |
| 15 | $68,973 |
| 20 | $96,742 |
| 25 | $135,678 |
| 30 | $190,254 |
These numbers demonstrate why the years until withdrawal input can have such a large impact.
However, real investment performance is not constant. Markets can rise and fall, and actual returns can differ substantially from a fixed annual assumption.
Why Other Taxable Income Matters
Other taxable income is an important consideration because a Roth conversion can increase your total taxable income.
Imagine two people each convert $30,000.
One has relatively little other taxable income, while the other already has substantial taxable income. Their conversions could have different tax consequences because the additional income may interact differently with their applicable tax brackets and other tax provisions.
That is why it is generally useful to examine the conversion together with your broader tax situation rather than considering the conversion amount alone.
The calculator provides a simplified estimated taxable income after conversion to make this relationship easier to visualize.
Should You Convert Your Entire Traditional IRA?
A Roth conversion does not necessarily have to involve the entire traditional retirement account.
Some people may consider converting:
- A fixed dollar amount each year
- An amount that fits within a desired tax bracket
- A portion of an account during lower-income years
- Larger amounts during particular tax-planning periods
The appropriate approach depends on individual circumstances.
A partial conversion can also provide flexibility. Instead of converting an entire account in one transaction, a person may evaluate different conversion amounts and compare the estimated tax implications.
You can use the calculator repeatedly with different conversion amounts to see how changing the amount affects the estimated results.
Paying Taxes on a Roth Conversion
One of the most important assumptions in this calculator is that the estimated conversion tax is paid separately from the retirement account.
For example, suppose you convert $25,000 and the estimated tax is $6,000.
Under the calculator’s assumption:
- $25,000 goes into the Roth projection.
- $6,000 is treated as the tax cost.
- The $6,000 is not deducted from the Roth investment amount.
This can differ significantly from using retirement funds to pay the conversion tax.
If taxes are paid from the retirement account, less money remains invested in the Roth account. Depending on age and circumstances, withdrawals used to pay taxes can also have additional tax consequences.
For this reason, anyone considering a substantial conversion should understand exactly how the tax payment will be funded.
Roth Conversion vs. Traditional Retirement Savings
Traditional and Roth accounts generally differ in when taxes are paid.
| Feature | Traditional Account | Roth Account |
|---|---|---|
| Contributions | Often made with pre-tax dollars | Generally made with after-tax dollars |
| Tax treatment of growth | Generally tax-deferred | Qualified growth can be tax-free |
| Tax on qualified retirement withdrawals | Generally taxable | Generally tax-free |
| Roth conversion | Not applicable | Can receive converted funds |
| Conversion tax | Not applicable to the account itself | Conversion may create taxable income |
The exact rules vary depending on the account type and circumstances.
A Roth conversion is therefore often viewed as a trade-off between paying taxes now and potentially receiving tax-free qualified withdrawals later.
Important Factors the Calculator Does Not Fully Model
The calculator provides a useful simplified estimate, but retirement tax planning involves more variables.
Important considerations can include:
Filing Status
Your tax filing status can affect applicable tax brackets and deductions.
Deductions
Taxable income is not necessarily the same as gross income. Deductions and other adjustments can affect the final tax calculation.
State Income Taxes
Some states impose individual income taxes while others do not. The calculator uses the tax rate you enter and does not independently determine your state tax liability.
Tax Brackets
A Roth conversion may push some of your income into a higher marginal tax bracket. A single flat rate can therefore simplify the real tax calculation.
Traditional IRA Basis
Not every traditional IRA dollar is necessarily taxable in the same way. After-tax contributions and basis can affect the taxable portion of a distribution or conversion.
Required Minimum Distributions
Retirement-account distribution rules can also affect long-term planning, particularly as you approach or enter the age at which required minimum distributions apply.
Investment Returns
The calculator assumes a constant annual return for projection purposes. Actual investment returns can vary considerably.
Future Tax Rates
No calculator can know exactly what tax rates will be in the future. Your future tax situation may be different from today’s.
How to Use Different Conversion Scenarios
One useful way to use the Roth Conversion Calculator is to test multiple scenarios.
For example, you could compare:
| Scenario | Conversion Amount | Tax Rate | Return | Years |
|---|---|---|---|---|
| Small Conversion | $10,000 | 22% | 7% | 20 |
| Moderate Conversion | $25,000 | 24% | 7% | 20 |
| Larger Conversion | $50,000 | 24% | 7% | 20 |
| Long-Term Conversion | $25,000 | 24% | 7% | 30 |
Changing only one input at a time can help you understand how each variable influences the results.
For instance, increasing the number of years can significantly increase the projected future value because compound growth has more time to work.
Benefits of Using a Roth Conversion Calculator
A calculator can make a complicated financial concept easier to understand.
Quick Estimates
Instead of performing compound-interest calculations manually, you can enter your assumptions and see the projected results.
Scenario Planning
You can test different conversion amounts, returns, tax rates, and time horizons.
Understanding Tax Costs
The estimated conversion tax helps demonstrate that a Roth conversion can create an immediate tax obligation.
Visualizing Long-Term Growth
The future-value calculation shows how a converted amount could grow under a selected return assumption.
Comparing Tax Cost and Investment Growth
The future value of the tax cost gives additional context about the potential opportunity cost of paying taxes today.
Common Roth Conversion Mistakes to Avoid
Converting Without Considering Taxes
A conversion can generate taxable income. Failing to plan for the tax bill can create a cash-flow problem.
Assuming the Calculator Gives an Exact Tax Bill
A marginal tax rate multiplied by the conversion amount is a simplified estimate. Your actual tax liability may be different.
Ignoring Other Income
Other taxable income can affect your overall tax situation, so consider the conversion alongside your other income.
Using Unrealistic Investment Returns
A high assumed return can make the projected future value look substantially larger. Conservative and realistic assumptions can provide more useful planning scenarios.
Forgetting the Time Horizon
The difference between 10 years and 30 years of compound growth can be substantial.
Paying Conversion Taxes From Retirement Funds Without Understanding the Consequences
Using retirement assets to pay the tax can reduce the amount available for future growth and may create additional tax considerations depending on your circumstances.
Roth Conversion Planning Tips
When exploring a Roth conversion, consider running several different scenarios rather than relying on one projection.
Start with a conservative investment-return assumption, then test moderate and higher assumptions separately. You can also vary the conversion amount to see how the estimated tax changes.
It can also be helpful to compare conversions made over multiple years rather than automatically assuming that one large conversion is appropriate.
Keep detailed records of the amount converted, the tax paid, and relevant account information. Tax professionals can help determine how the conversion should be reported and how other aspects of your financial situation may affect the transaction.
Most importantly, distinguish between a calculator projection and a personalized tax calculation. The calculator is useful for education and preliminary planning, but it does not replace professional tax or financial advice.
Frequently Asked Questions About Roth Conversions
1. What is a Roth conversion?
A Roth conversion is generally the process of moving money from a traditional tax-deferred retirement account into a Roth account. The converted amount may be taxable in the year of conversion, depending on the account’s tax basis and other circumstances.
2. How is the Roth conversion tax calculated?
This calculator estimates the tax by multiplying the conversion amount by the estimated marginal tax rate:
Conversion Tax = Conversion Amount × Tax Rate
Actual taxes can differ because the U.S. tax system is progressive and other factors may affect your taxable income.
3. Can I convert my entire traditional IRA to a Roth IRA?
It may be possible to convert the entire eligible balance, but doing so can create a significant taxable-income increase. Whether a full conversion is appropriate depends on your individual financial and tax circumstances.
4. Does a Roth conversion increase taxable income?
Generally, the taxable portion of a Roth conversion is included in income for the conversion year. The calculator estimates this by adding the conversion amount to the other taxable income entered.
5. Does a Roth conversion have to be done all at once?
No. Conversions can potentially be performed in different amounts and at different times. Some retirement savers evaluate partial conversions over multiple years.
6. What does the 7% return assumption mean?
The calculator starts with a 7% annual investment-return assumption. This means the projection assumes the investment grows by 7% each year, compounded annually. It does not mean an actual investment will earn 7% every year.
7. Why does the calculator show the future value of the tax cost?
Paying taxes today uses money that could otherwise potentially be invested. The calculator compounds the estimated tax cost at the same assumed investment return to illustrate that potential opportunity cost.
8. Should I pay Roth conversion taxes from my retirement account?
The calculator assumes that the tax is paid separately. Whether you should use retirement funds or outside funds depends on your circumstances, age, cash reserves, tax situation, and retirement strategy.
9. What happens if I convert more than my retirement account balance?
The calculator does not allow a conversion amount greater than the entered traditional IRA or 401(k) balance. Entering an amount above the balance produces a validation message.
10. What is the future value of a Roth conversion?
Future value represents what the converted amount could potentially become after earning the assumed annual return for the selected number of years. It is calculated using compound growth.
11. Is the Roth conversion tax rate the same as my overall tax rate?
Not necessarily. The calculator asks for an estimated marginal tax rate. Your effective tax rate can be different from your marginal rate, and a conversion can affect multiple portions of your taxable income.
12. Does this calculator include state income tax?
The calculator does not independently calculate state tax. If you want to account for state taxes, you would need to incorporate an appropriate assumption into your broader tax planning.
13. Can I use this calculator for a traditional 401(k)?
The calculator includes a traditional IRA / 401(k) balance field and is designed for a simplified conversion estimate. Actual 401(k)-to-Roth conversion rules can depend on the specific plan and transaction structure.
14. Is the estimated net future value guaranteed?
No. It is a mathematical projection based on the assumptions entered. Investment returns, tax laws, inflation, and personal circumstances can change, so actual results may differ substantially.
15. Should I consult a tax professional before converting?
For a significant Roth conversion, professional advice can be useful because your actual tax consequences may involve factors that a simple calculator does not model, including tax brackets, deductions, basis, state taxes, and other income.
Final Thoughts
The Roth Conversion Calculator provides a straightforward way to explore the potential financial effects of converting money from a traditional retirement account to a Roth account. By considering the conversion amount, estimated marginal tax rate, other taxable income, investment return, and time horizon, you can see how an immediate tax cost relates to potential long-term compound growth.
The most useful feature of a calculator like this is its ability to support scenario analysis. Try different conversion amounts and time horizons rather than relying on a single estimate. A smaller conversion, for example, may produce a different immediate tax cost and projected future value than a larger conversion.
Remember that the calculations are estimates. Actual Roth conversion taxation can be more complicated than the simplified formulas used here, and investment performance is never guaranteed. Use the results as a starting point for retirement-planning discussions and consider obtaining personalized tax or financial advice before making a major conversion decision.