How to use this calculator
Enter your filing status and the income you expect this year before converting — wages, pensions, interest and taxable Social Security. The calculator subtracts the 2026 standard deduction, finds the bracket you land in, and tells you how much you can convert before any of it is taxed at a higher rate. Then set the amount you want to convert to see the federal tax, the effective rate on the converted amount, and the long-term result against leaving the money where it is.
How much tax will you pay on a Roth conversion?
A converted amount is not taxed at a single flat rate. It stacks on top of the income you already have and fills each bracket in turn, so the effective rate is usually lower than your top bracket — unless the conversion is large enough to spill into the next one. That is the number most free Roth conversion calculators get wrong, because they ask you for “your tax rate” and multiply.
2026 federal income tax brackets
These apply to taxable income — your income after the standard deduction, which is $16,100 for single filers and $32,200 for married couples filing jointly in 2026.
| Rate | Single | Married filing jointly |
|---|---|---|
| 10% | $0 and up | $0 and up |
| 12% | $12,400 and up | $24,800 and up |
| 22% | $50,400 and up | $100,800 and up |
| 24% | $105,700 and up | $211,400 and up |
| 32% | $201,775 and up | $403,550 and up |
| 35% | $256,225 and up | $512,450 and up |
| 37% | $640,600 and up | $768,700 and up |
Source: IRS Revenue Procedure 2025-32, the 2026 inflation adjustments.
What is a Roth conversion?
A Roth conversion moves money from a pre-tax account — a traditional IRA or an old 401(k) — into a Roth IRA. You pay ordinary income tax on the amount you convert in the year you do it. In exchange, that money grows tax-free from then on, and qualified withdrawals in retirement are completely tax-free. Roth IRAs also have no required minimum distributions during your lifetime, so the balance can keep compounding untouched.
When does a Roth conversion make sense?
The math tends to favor converting when:
- You expect your tax rate in retirement to be equal to or higher than it is today.
- You can pay the conversion tax from outside savings, leaving the full converted amount to grow in the Roth.
- The money has many years left to compound before you need it.
- You're in a temporarily low-income year — early retirement, a career gap, or a down market that has lowered your balance.
- You want to reduce future required minimum distributions or leave tax-free money to heirs.
What this calculator leaves out
It models federal income tax only. A conversion can also raise your Medicare premiums through IRMAA, change how much of your Social Security is taxable, and push long-term capital gains into a taxed band. Where you live matters too — some states tax retirement income and some do not. Run the numbers through our IRMAA calculator, the Family Tax Rate calculator and your state retirement tax guide alongside this one.
This calculator is a simplified planning estimate for educational purposes and is not tax advice. Conversion decisions depend on your full tax picture — consult a qualified tax or financial professional before converting.
Frequently asked questions
How much tax will I pay on a Roth conversion?
The amount you convert is added to your taxable income for the year and taxed at ordinary income rates. It is not taxed at one flat rate: the conversion stacks on top of your other income and fills each bracket in turn. Convert $50,000 on top of $90,000 of other income as a married couple in 2026, and part of it is taxed at 12% and part at 22% — an effective rate well below your top bracket. The calculator above works this out bracket by bracket.
How much can I convert without going into a higher tax bracket?
Subtract your standard deduction from your income, then look at where that lands in the 2026 brackets. The gap between that figure and the start of the next bracket is how much you can convert at your current rate. The calculator shows this as "room left in your bracket", so you can size a conversion to fill a bracket exactly and convert the rest in a later year.
Is a Roth conversion worth it?
A Roth conversion generally pays off when you expect your tax rate in retirement to be the same or higher than it is today, when you can pay the conversion tax from outside savings rather than the IRA, and when the money has years left to grow tax-free. Paying the tax from the IRA shrinks the amount that reaches the Roth, and before age 59½ the withheld amount can also trigger a 10% penalty.
When is the best time to do a Roth conversion?
Low-income years are ideal — early retirement before Social Security and required minimum distributions begin, a gap year between jobs, or any year a market dip has temporarily lowered your IRA balance. Converting in those windows moves more shares into the Roth for the same tax bill.
Do I have to pay the Roth conversion tax all at once?
The tax is due for the tax year in which you convert, typically through estimated taxes or your annual return. You cannot spread a single conversion's tax over several years, but you can spread the conversions themselves — converting a slice each year keeps you in a lower bracket and smooths the total cost.