Roth Conversion Calculator: Tax Cost Now vs. Tax-Free Later
Enter the amount you would convert from a traditional IRA or 401(k) to a Roth, along with your other taxable income, filing status, and state. You get the tax bill now, the bracket the conversion lands in, and what the money is worth at withdrawal compared with leaving it where it is.
Pre-tax dollars moving from a traditional IRA or 401(k) to a Roth
After deductions: the 2026 standard deduction is $16,100 for your filing status
Statewide income tax only; local taxes excluded
How long the converted money stays invested
7% is a common long-run stock market assumption
Pay the tax bill from
Your best guess at the marginal rate on withdrawals later
Tax cost now
$15,571
$11,086 federal + $4,485 state, 31.1% of the conversion
Bracket the conversion lands in
24%
starts in the 22% bracket and climbs to 24%
Room left in this bracket
$91,775
convert up to this much more at 24% before the next step up
Tax-free at withdrawal (year 20)
$193,484
the full $50,000 grows 20 years at 7.0%
If left traditional, after tax
$211,171
$50,000 grown and taxed at 22%, plus the $15,571 you kept outside, also grown
Staying traditional comes out ahead by
$17,687
31.1% paid now vs 22% expected later; the lower rate wins
One year vs spreading it out
| Spread over | Converted per year | Tax per year | Total tax | Effective rate | Top bracket |
|---|---|---|---|---|---|
| 1 year (all at once) | $50,000 | $15,571 | $15,571 | 31.1% | 24% |
| 2 years | $25,000 | $7,660 | $15,319 | 30.6% | 22% |
| 3 years | $16,667 | $5,051 | $15,154 | 30.3% | 22% |
| 4 years | $12,500 | $3,750 | $15,000 | 30.0% | 22% |
Each row assumes the same other income every year and ignores growth on the unconverted portion and future bracket changes. Spreading helps only when a single-year conversion would climb into a higher bracket.
Educational estimate for the 2026 tax year, not tax advice. Federal figures follow IRS inflation adjustments; state estimates use statewide rates and standard deductions only and exclude local income taxes (city, county, school district), State Disability Insurance, and credits. Where a state publishes separate married tables, married thresholds may be approximated. Verify your exact withholding with a tax professional or your payroll provider.
California: Excludes State Disability Insurance withholding (uncapped). The 1% mental health surtax threshold is approximated for married filers.
What a conversion actually does
A Roth conversion moves money from a pre-tax account (a traditional IRA or an old 401(k)) into a Roth, and the amount moved is added to your taxable income for the year. You pay ordinary income tax on it now; in exchange, qualified withdrawals later come out tax-free and the account never faces required minimum distributions during your lifetime. There is no age limit and no penalty on the converted dollars themselves. The trade is a known tax bill today for an unknown one avoided later.
The stacking math, bracket by bracket
The converted amount stacks on top of whatever taxable income you already have. The calculator taxes your base income, then taxes base plus conversion, and the difference is the cost of the conversion; state tax is stacked the same way using statewide rates. Because federal brackets step up, the first converted dollars fill the room left in your current bracket at that rate, and only the overflow moves into the next one. That is what filling brackets means: converting up to the ceiling of a bracket and stopping before the jump. The room-left stat shows how much space you have.
Worked example: the same $50,000 in two different years
A single filer in Colorado converts $50,000. In a year with $30,000 of taxable income, the conversion starts in the 12% bracket and tops out at 22%: $8,960 federal plus $2,200 state, $11,160 in all, about 22.3% of the amount. In a year with $150,000 of taxable income, the whole conversion sits in the 24% bracket: $14,200, or 28.4%. Same account, same dollars, $3,040 apart, purely because of the year it was done.
Two details that change the answer
Paying the tax from outside money
If the tax comes out of the conversion itself, less lands in the Roth and less grows tax-free. Paying from savings keeps the full amount sheltered, which is why the comparison also counts the outside money you would otherwise have kept. Under 59½ there is a second reason: dollars pulled from the IRA to cover the tax are a distribution, not a conversion, and can owe the early withdrawal penalty.
The five-year clock
Each conversion starts its own five-year clock. Before 59½, converted principal taken out inside that window can owe the penalty; earnings are tax-free once you are 59½ and your first Roth has been open five years. For money you plan to leave alone for a decade or more, the clock rarely bites.
When a conversion is worth modeling
Low-income years are the window: a sabbatical, early retirement before Social Security starts, a year between jobs, or the years before required minimum distributions begin (the RMD calculator shows what those would look like). The verdict here turns on one comparison: the effective rate you pay now against the rate you expect at withdrawal. Growth cancels out of that comparison, which is why the years and return sliders change the size of the numbers but not the winner. The Roth vs. traditional calculator makes the same decision for new contributions, and our backdoor Roth guide covers conversions used to get around income limits. None of this is advice; it is arithmetic to bring to a professional.
Frequently asked questions
Is a Roth conversion taxed as regular income?
Yes. The converted amount is added to your ordinary income for the year and taxed at your marginal federal rate, stacked on top of everything else you earned. Most states with an income tax count it too. Nothing is withheld automatically unless you ask for it, so many people set the tax money aside or pay estimates during the year.
Is there a penalty for converting before 59½?
Not on the conversion itself, at any age. The catch is the tax bill: if you pay it with money taken out of the IRA rather than from savings, that portion is a distribution instead of a conversion, and it can owe the early withdrawal penalty plus tax of its own. Paying from outside money avoids that.
Should I convert all at once or spread it over several years?
The table in the calculator shows the difference. Spreading a conversion keeps each year's slice inside lower brackets, which can cut the total tax, at the cost of leaving the unconverted portion in the pre-tax account longer. Which is better depends on your other income each year and where the brackets fall, so compare the rows rather than assuming.
What is the five-year rule for Roth conversions?
Each conversion has its own five-year clock. If you are under 59½ and withdraw converted principal within five years of that conversion, the early withdrawal penalty can apply even though you already paid income tax on it. Earnings come out tax-free once you are 59½ and your first Roth account has been open at least five years.
How accurate is this calculator?
It stacks the conversion on the taxable income you enter using the 2026 federal brackets and statewide rates. It does not model Medicare premium surcharges, credit phase-outs, the pro-rata rule for non-deductible IRA basis, or a change in your other income between years. Educational estimate for the 2026 tax year, not tax advice. Federal figures follow IRS inflation adjustments; state estimates use statewide rates and standard deductions only and exclude local income taxes (city, county, school district), State Disability Insurance, and credits. Where a state publishes separate married tables, married thresholds may be approximated. Verify your exact withholding with a tax professional or your payroll provider.
Does this calculator save my numbers?
No. Everything runs in your browser and nothing you type is stored or sent anywhere.
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