Roth Conversion Calculator
This Roth conversion calculator evaluates whether converting a Traditional IRA to a Roth IRA makes financial sense. Enter the conversion amount, your other income for the year, filing status, years to retirement, expected return and expected tax rate in retirement. The calculator computes the federal income tax cost of the conversion using 2025 tax brackets, then projects the after-tax value of the Roth balance versus keeping the money in a Traditional IRA, accounting for tax-free growth in the Roth and taxable withdrawals from the Traditional. There is no income limit on conversions, making this strategy available to high earners who are ineligible for direct Roth contributions. A backdoor Roth is a common strategy where you make a non-deductible Traditional IRA contribution and immediately convert it to a Roth, but pro-rata rule complications apply if you hold other pre-tax IRA balances. The calculator shows the tax cost, marginal rate on the conversion, projected Roth balance, projected Traditional after-tax value and net Roth advantage in dollars. A breakdown verdict explains whether conversion makes sense based on your tax assumptions.
Converting $30,000 from a Traditional IRA with $85,000 other income (single) costs -- in federal tax this year. After 20 years at 7%/year, the Roth advantage over leaving it in the Traditional IRA is --.
How the Roth conversion calculation works
A Roth conversion moves pre-tax dollars from a Traditional IRA to a Roth IRA. The converted amount is treated as ordinary income and taxed using 2025 federal income tax brackets, as described in IRS Topic 413 and IRS Publication 590-A. This calculator uses the standard deduction for the chosen filing status.
Total income = other income + conversion amount
Tax on total = sum of bracket rates applied to (total income - standard deduction)
Tax on other income only = same brackets applied to (other income - standard deduction)
Tax on conversion = Tax on total - Tax on other income
Marginal rate on conversion = Tax on conversion / conversion amount
Roth FV = conversion x (1 + r)^n [tax-free at withdrawal]
Traditional FV (if not converted) = conversion x (1 + r)^n x (1 - retirement_tax_rate)
Net Roth advantage = Roth FV - Traditional FV
Worked example
Single filer, other income $85,000, conversion $30,000, 20 years at 7%, retirement rate 25%:
- Standard deduction (single 2025) = $15,000
- Tax on $85,000 (before conversion): $85,000 - $15,000 = $70,000 taxable; tax = $9,647
- Tax on $115,000 (with conversion): $115,000 - $15,000 = $100,000 taxable; tax = $17,307
- Tax on conversion = $17,307 - $9,647 = $7,660
- Marginal rate on conversion = $7,660 / $30,000 = 25.5%
- Roth FV = $30,000 x (1.07)^20 = $116,091 (tax-free)
- Traditional after-tax FV = $116,091 x (1 - 0.25) = $87,068
- Net Roth advantage = $116,091 - $87,068 = $29,023
In this example, the Roth conversion is advantageous because the assumed retirement rate (25%) is higher than the effective rate on the conversion (~25.5% is nearly the same, making this a close call; small changes in the retirement rate assumption change the verdict).
When to consider a Roth conversion
The ideal time to convert is in a year when your taxable income is unusually low relative to your long-term expectations. Common windows include: the gap between retirement and age 73 when RMDs begin (before RMDs force large withdrawals at higher rates); a year with large deductions (such as a year with high charitable giving); a year after a job loss or business loss that reduces income; or a year when a market decline has reduced the value of the IRA (so you convert fewer dollars at the same tax cost and capture more subsequent growth tax-free).
Conversions are most powerful when you pay the tax from funds outside the IRA. If you withhold from the converted amount to pay the tax, you reduce the amount in the Roth and may owe a 10% penalty on the withheld amount if you are under age 59-and-a-half.
The five-year rule for conversions
Each Roth conversion has its own five-year holding period for penalty-free withdrawal of converted amounts (if you are under 59-and-a-half). This is separate from the five-year rule that applies to Roth IRA earnings. The ordering rules for Roth IRA distributions are: contributions first (always penalty-free and tax-free), then conversions (in FIFO order, subject to the five-year rule if under 59-and-a-half), then earnings last. Source: IRS Publication 590-B.
Roth conversion calculator: frequently asked questions
What is a Roth conversion?
A Roth conversion is the process of moving money from a Traditional IRA (or other pre-tax retirement account) into a Roth IRA. The converted amount is treated as ordinary income in the year of conversion and taxed at your marginal rate. After the conversion, the money grows tax-free in the Roth IRA and qualified withdrawals are not taxable. There is no income limit on conversions; anyone can convert regardless of income.
Is there an income limit for Roth conversions?
No. There is no income limit on Roth IRA conversions. This is different from direct Roth IRA contributions, which phase out at higher incomes. Any Traditional IRA, SEP-IRA, or SIMPLE IRA balance (after a two-year waiting period for SIMPLE IRAs) can be converted to a Roth IRA at any income level. Source: IRS Publication 590-A.
How is the tax on a Roth conversion calculated?
The converted amount is added to your ordinary income for the year and taxed at your marginal federal income tax rate on the combined income. For example, if your regular income is $85,000 (single filer) and you convert $30,000, your total income is $115,000, which pushes some income into the 22% bracket. The calculator above computes the marginal rate on the conversion using 2025 federal brackets. State income tax may also apply; this calculator covers federal tax only.
What is the backdoor Roth IRA?
The backdoor Roth IRA is a strategy where a taxpayer above the Roth contribution income limit makes a non-deductible Traditional IRA contribution and then immediately converts it to a Roth IRA. Because the contribution was made with after-tax dollars, little or no tax is owed on the conversion (assuming no pre-existing pre-tax IRA balances, due to the pro-rata rule). The strategy is legal and widely used, but requires careful tracking on IRS Form 8606.
Should I do a partial or full Roth conversion?
Many taxpayers do partial conversions each year to manage their tax bracket. A common strategy is to convert only enough each year to fill up the current tax bracket without pushing into the next higher bracket. For example, if your income is $60,000 as a single filer, you could convert up to $43,350 before hitting the 22% bracket ($103,350 minus $60,000). Spreading conversions over several low-income years (such as early retirement before RMDs begin) can reduce the total tax cost.
When does a Roth conversion make the most sense?
Roth conversions are most advantageous when: (1) your current tax rate is lower than your expected retirement rate; (2) you have funds outside the IRA to pay the conversion tax (so the Roth account itself can grow unimpaired); (3) you have many years of tax-free growth ahead; (4) you expect large RMDs from Traditional IRAs that would push you into higher brackets; or (5) you want to reduce the size of your taxable estate. The break-even analysis depends heavily on assumptions about future tax rates.
Official sources
- Roth conversion rules: IRS Publication 590-A, Contributions to Individual Retirement Arrangements.
- Roth IRA distributions and ordering rules: IRS Publication 590-B, Distributions from Individual Retirement Arrangements.
- Roth conversions overview: IRS Topic 413, Rollovers from Retirement Plans.
Reviewed by the CalculatorHub team, edited by James Graham, 13 June 2026. See our methodology. General information only, not financial or tax advice.