How to Use This Calculator
- 1
Enter Conversion Amount
Input the total amount you plan to convert from your Traditional IRA to a Roth IRA, such as $20,000.
- 2
Specify Current Tax Rate
Enter your current marginal income tax rate, which will apply to the converted amount today.
- 3
Estimate Future Tax Rate
Provide the tax rate you anticipate paying on withdrawals in retirement. If this is higher than your current rate, a Roth conversion is generally more attractive.
- 4
Input Years Until Retirement
State the number of years your Roth IRA will have to grow tax-free before you reach retirement.
- 5
Provide Annual Rate of Return
Enter the expected average annual investment return for your portfolio.
- 6
Review Your Results
Review the Roth IRA at Retirement, Conversion Tax Cost, Traditional IRA (After-Tax), Conversion Advantage, and After-Tax Amount Invested cards. The Conversion Analysis insights panel shows the tax rate spread, growth multiplier, and tax-equivalent yield with a Roth vs Traditional breakdown bar.
Example Calculation
A mid-career professional is considering converting $20,000 from their Traditional IRA to a Roth IRA, currently in the 25% bracket and expecting 30% in retirement.
Conversion Amount ($)
20,000
Current Tax Rate (%)
25
Expected Future Tax Rate (%)
30
Years Until Retirement (yrs)
15
Annual Rate of Return (%)
6
Results
Roth IRA at Retirement
$35,948
Conversion Tax Cost
$5,000
Traditional IRA (After-Tax)
$33,552
Conversion Advantage
$2,397
After-Tax Amount Invested
$15,000
Tips
Convert in a Low Income Year
Strategically convert Traditional IRA funds to Roth during years when your income is lower than usual — a career break, reduced hours, or large deductions can minimize the conversion tax bill.
Pay Taxes from Outside Funds
If possible, pay the conversion taxes from a non-retirement account. Paying the tax directly from the converted amount reduces the principal that can grow tax-free in the Roth, diminishing the long-term advantage.
Consider Partial Conversions
You don't have to convert your entire Traditional IRA at once. Staggering conversions over several years can help manage your tax liability and keep you within a desired tax bracket.
Watch the IRMAA Thresholds
Large conversions can push your MAGI above Medicare IRMAA thresholds, adding premium surcharges two years later. Plan conversion amounts to stay below the $103,000 single or $206,000 joint thresholds.
Strategic Tax Planning with Roth IRA Conversions
The Roth IRA Conversion Calculator empowers individuals to make informed decisions about their retirement savings, comparing the long-term after-tax growth of a Roth IRA against a Traditional IRA. By estimating the tax cost of conversion, future retirement values, and the conversion advantage, users can strategically plan for tax-free income in retirement.
For instance, converting $20,000 from a Traditional IRA with a 25% current tax rate, expecting a 30% future tax rate, and earning 6% over 15 years results in a Roth IRA balance of $35,948 — a $2,397 advantage over keeping the funds in a Traditional IRA. This tool is critical for optimizing retirement portfolios and navigating tax planning in 2026.
Modeling After-Tax Retirement Growth
The calculator models the future value of your retirement savings under two scenarios: converting to a Roth IRA now versus keeping funds in a Traditional IRA. The core difference lies in when taxes are paid — upfront for Roth conversions, or upon withdrawal for Traditional IRAs.
The calculations involve:
- Conversion Tax Cost:
conversion tax cost = conversion amount x (current tax rate / 100) - Amount Invested in Roth:
roth invested = conversion amount - conversion tax cost - Roth IRA at Retirement (FV_Roth):
FV_Roth = roth invested x (1 + r)^n - Traditional IRA at Retirement (FV_Traditional):
FV_Traditional = conversion amount x (1 + r)^n x (1 - future tax rate / 100)
Where:
ris the annual rate of return (as a decimal).nis the number of years until retirement.
The conversion advantage is the difference between FV_Roth and FV_Traditional.
Comparing Roth vs. Traditional for a $20,000 Conversion
Let's compare the outcomes for a $20,000 IRA conversion with the following parameters:
- Conversion Amount: $20,000
- Current Tax Rate: 25%
- Expected Future Tax Rate: 30%
- Years Until Retirement: 15 years
- Annual Rate of Return: 6% (0.06 as a decimal)
Here's the step-by-step comparison:
- Calculate Conversion Tax Cost:
Conversion Tax Cost = $20,000 x (25 / 100) = $5,000 - Calculate Amount Invested in Roth:
Roth Invested = $20,000 - $5,000 = $15,000 - Calculate Roth IRA at Retirement:
FV_Roth = $15,000 x (1.06)^15 = $15,000 x 2.3966 = $35,948 - Calculate Traditional IRA (After-Tax) at Retirement:
FV_Traditional = $20,000 x (1.06)^15 x 0.70 = $47,931 x 0.70 = $33,552 - Calculate Conversion Advantage:
Conversion Advantage = $35,948 - $33,552 = $2,397
In this scenario, the Roth conversion provides an advantage of approximately $2,397 by retirement, primarily due to the higher expected future tax rate.
When a Roth Conversion Is Most Beneficial
Roth IRA conversions are a powerful tax planning strategy, particularly for individuals who anticipate their marginal income tax rates will be higher in retirement than they are today. The primary benefit is tax-free growth and tax-free withdrawals of all earnings in retirement, provided the five-year rule and age requirements are met.
This can be especially advantageous for high-income earners who may be subject to RMDs (Required Minimum Distributions) from Traditional IRAs, as Roth IRAs are exempt from RMDs for the original owner. Converting during a year when you're in the 22% or 24% bracket to avoid future taxes at a projected 32% rate can lead to significant savings over a 20-30 year retirement horizon.
When a Roth Conversion May Not Be Optimal
If you anticipate being in a lower tax bracket in retirement than you are currently, paying taxes now on a conversion would be counterproductive. Additionally, if you need access to the converted funds within five years and are under 59 1/2, you could face a 10% early withdrawal penalty on the earnings portion.
A large conversion could also push you into a higher tax bracket in the year of conversion, triggering higher taxes on other income or impacting eligibility for tax credits. For example, converting $100,000 might add $24,000 to $37,000 in immediate tax liability, depending on your marginal bracket.
Frequently Asked Questions
What is a Roth IRA conversion?
A Roth IRA conversion moves pre-tax funds from a Traditional IRA into a Roth IRA. You pay ordinary income tax on the converted amount in the year of conversion, but all future qualified withdrawals — including earnings — are completely tax-free. There is no income limit for conversions.
When does a Roth IRA conversion make sense?
A Roth conversion typically makes sense when you expect your income tax rate to be higher in retirement than it is today. For example, converting $20,000 at a 25% current rate while expecting a 30% future rate creates a $2,397 advantage over 15 years at 6% returns. It's also beneficial if you want to leave tax-free assets to heirs or avoid Required Minimum Distributions.
What is the five-year rule for Roth conversions?
Each Roth IRA conversion has its own five-year holding period. If you withdraw the converted amount before five years and you are under 59 1/2, you owe a 10% early withdrawal penalty. After age 59 1/2, the five-year rule for conversions no longer applies.
What is the pro-rata rule for Roth conversions?
The pro-rata rule applies when you have both pre-tax and after-tax (nondeductible) funds across all your Traditional, SEP, and SIMPLE IRAs. The IRS mandates that a proportional amount of any conversion is considered taxable, based on the ratio of your pre-tax to total IRA balances — you cannot selectively convert only after-tax funds.
How does the Conversion Analysis insights panel help?
The insights panel shows your tax rate spread (current vs future), the growth multiplier per dollar invested, and your tax-equivalent yield. The breakdown bar visually compares Roth vs Traditional retirement values, making it easy to see which strategy wins for your specific inputs.