Enter the conversion
Add the amount you are considering moving from a traditional IRA to a Roth IRA. The amount cannot exceed the combined IRA balance in this simplified model.
Roth conversion planning
Estimate model
Roth Conversion Calculator
Use this Roth conversion calculator to estimate how much of a traditional IRA conversion may be taxable, the federal and state tax cost, and what the converted dollars could be worth in a Roth account over time.
Runs in your browser
Educational estimate, not tax advice
Build a scenario
Enter your conversion details
Use your own approximate account figures and marginal tax rates. The result is a planning range, not a tax return calculation.
Your estimate
See the taxable share and projected value
The calculator separates the estimated tax bill from the amount that continues compounding inside the Roth account.
Estimated taxable conversion
Example
$50,000of this conversion
The simplified pro-rata share is 100%; basis can reduce the taxable portion.
Estimated tax cost
Example
$14,500
If paid from the conversion, shown over 20 years
Roth dollars invested$50,000
Illustrative future Roth value$160,357
Combined entered tax rate29%
Taxable share of the conversion
The bar reflects the share treated as pre-tax under the simplified balance-and-basis model. A real return may require Form 8606 and professional review.
0% taxable100% taxable
Show calculation summary
| Planned conversion | $50,000 |
|---|---|
| Estimated taxable amount | $50,000 |
| Estimated tax cost | $14,500 |
| Roth amount invested | $50,000 |
| Future Roth value | $160,357 |
| Basis applied | $0 |
Example output uses a $50,000 conversion, $100,000 total IRA balance, zero basis, 29% combined rate, 20 years and a 6% return.
This simplified model does not determine your tax bracket, filing status, withholding, penalties or final IRS liability.
How to use it
Run a Roth conversion tax scenario in four steps
Start with a conservative scenario, then change one input at a time. The calculator is most useful when you compare several conversion amounts rather than treating one output as a yes-or-no recommendation.
Add balance and basis
Enter the total traditional, SEP and SIMPLE IRA balance plus any after-tax basis. Those values drive the estimated taxable share under a simplified pro-rata calculation.
Choose tax assumptions
Use your estimated federal and state marginal rates. If you pay tax from outside cash, the full conversion continues into the Roth projection; withholding reduces the invested amount.
Read the result
Review the taxable conversion, estimated tax cost, Roth dollars invested and future value. Then test a smaller or staged conversion to see how the tax cost changes.
Read the output
What this Roth conversion calculator estimates
A conversion is not the same as a regular Roth IRA contribution. It moves money from a pre-tax or mixed IRA into a Roth IRA and may add taxable income for the year of the conversion.
Taxable conversion
The calculator estimates the portion of the conversion that is not covered by after-tax basis. With no basis entered, the example treats the full conversion as taxable. A real pro-rata calculation can involve all of your traditional, SEP and SIMPLE IRAs.
Estimated tax cost
The taxable amount is multiplied by the federal and state rates you enter. This is deliberately transparent: it does not pretend to know your filing status, deductions, credits, bracket transitions, withholding or other income.
Roth dollars invested
When tax is paid with outside cash, the planned conversion remains invested in the Roth projection. When tax is withheld from the conversion, the calculator subtracts the estimate before projecting growth.
Future Roth value
The future value is a mathematical scenario using your return and time inputs. It is not a forecast, guarantee or estimate of a specific fund. Returns can be negative or uneven, and fees can reduce results.
Rules and boundaries
Why basis and the pro-rata rule matter
The hardest part of a Roth conversion estimate is usually not the compound-growth formula. It is deciding how much of the conversion is taxable when an investor has a mixture of pre-tax IRA money and nondeductible basis.
This page uses a simplified balance-and-basis model: total basis is divided by the combined traditional, SEP and SIMPLE IRA balance, and the remaining share is applied to the planned conversion. It is useful for scenario comparison, but it is not a replacement for Form 8606 or a tax professional who can review your complete IRA history.
A conversion can increase adjusted gross income and may affect other items such as credits, Medicare-related premiums, taxation of benefits or state tax. The calculator does not model those interactions. Entering a marginal rate is a way to explore sensitivity, not a determination of the rate that will apply.
Tax timing also matters. Paying the tax from another source may leave more money inside the Roth account, while withholding from the conversion leaves less principal to compound. Either choice can have cash-flow, penalty and investment consequences that are outside this page.
| Calculation style | Browser-local estimate |
|---|---|
| Tax rate input | User-entered marginal federal plus state rates |
| Basis treatment | Simplified pro-rata share |
| Growth model | Constant annual return and time horizon |
Worked example
A staged conversion can make the tax trade-off easier to see
Example: $50,000 conversion, $100,000 combined IRA balance, no after-tax basis, 24% federal rate, 5% state rate, and a 20-year horizon.
Conversion$50,000
Estimated taxable share100%
Estimated tax cost$14,500
Assumed return6% for 20 years
The output is not a recommendation to convert. It gives the investor a comparison point: paying the estimated tax with outside cash leaves the full $50,000 in the Roth projection, while withholding the estimate reduces the amount that compounds. Testing $20,000, $30,000 and $50,000 can show whether a staged approach better matches available cash and the investor's tolerance for a larger tax year.
Use with care
Important assumptions and limitations
Financial calculators are clearer when they state what they leave out. Keep these limits with any saved or shared result.
Not a tax return
The model does not calculate taxable income, tax brackets, deductions, credits, withholding, filing status, estimated payments or penalties. It applies the rates you type to the estimated taxable portion.
Not an investment forecast
The growth result holds the return constant. Real markets change, losses happen, fees matter and the account may not be invested in a way that matches the assumption.
Account scope matters
The simplified basis estimate expects the combined traditional, SEP and SIMPLE IRA balance. Employer plans, inherited accounts, rollovers, recharacterizations and other facts can change the analysis.
Check before acting
Verify current IRS rules, deadlines and reporting requirements. A qualified tax professional can help evaluate whether a conversion fits your income, cash reserves, retirement timing and estate plan.
Questions
Roth conversion calculator FAQ
These answers explain the model so you can decide which inputs deserve a closer review.
What does a Roth conversion calculator estimate?
It estimates the taxable portion of a traditional IRA conversion, applies the federal and state marginal rates you enter, and projects the amount that could remain invested in the Roth account. It does not determine your final tax bill.
Is a Roth conversion the same as a Roth IRA contribution?
No. A contribution is a regular deposit subject to contribution rules. A conversion moves money from another eligible retirement account into a Roth IRA and can create taxable income even when no new cash enters the retirement system.
Why does the calculator ask for my total IRA balance?
A simplified pro-rata estimate needs the combined traditional, SEP and SIMPLE IRA balance to compare pre-tax money with after-tax basis. Using only the account you plan to convert can understate the taxable share.
What if I have after-tax basis in an IRA?
Enter the basis you believe has already been taxed. The model applies it proportionally across the combined balance. Keep your records and review Form 8606 requirements because the simplified estimate cannot verify your basis history.
Should I pay conversion tax from outside cash?
The calculator shows why the funding source matters: outside cash leaves more of the conversion invested in the Roth account, while withholding reduces the principal. The better choice depends on your cash flow, age, tax position and professional advice.
Can I use this calculator for a backdoor Roth?
Only as a rough illustration of the taxable-share concept. Backdoor Roth planning can involve contribution eligibility, basis, timing and the pro-rata rule, so this page should not be treated as a complete backdoor Roth workflow.
Is this Roth conversion calculator tax advice?
No. It is a browser-based educational estimate. Confirm current IRS guidance and your personal facts with a qualified tax professional before making a conversion or changing withholding.
Keep the decision in context
Compare scenarios before you choose a conversion amount
A useful next step is to compare several conversion sizes, tax-payment sources and time horizons. For direct contribution limits and Roth growth assumptions, return to the main Roth IRA calculator.
Open the Roth IRA calculator