How to use this calculator
Enter your traditional IRA balance and the amount you're thinking of converting. Add your current tax rate, the tax rate you expect in retirement, how many years the money has to grow, and an assumed annual growth rate. The calculator shows the tax you'd pay now, the projected future value in each scenario, and the net benefit (or cost) of converting. Adjust the inputs to test different conversion amounts and timing.
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.
Understanding the tax impact
The converted amount stacks on top of your other income for the year, so a large one-time conversion can spill into a higher bracket, raise your Medicare (IRMAA) premiums, or affect the taxation of Social Security. That's why many households convert in stages, filling up a target bracket each year rather than converting everything at once. If IRMAA is a concern, run the numbers through our IRMAA calculator and Family Tax Rate calculator 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 from a traditional IRA is added to your taxable income for the year and taxed at your ordinary income tax rate. If you convert $50,000 and you're in the 24% bracket, you'd owe roughly $12,000 in federal tax. A large conversion can push part of the amount into a higher bracket, so many people convert gradually over several years.
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 (not the IRA itself), and when the money has years left to grow tax-free. The calculator above compares tax paid now against tax avoided later so you can see the trade-off for your own numbers.
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 means more shares move to 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 with your estimated taxes or annual return. You cannot spread a single conversion's tax over multiple years, but you can spread the conversions themselves — converting a portion each year keeps you in a lower bracket and smooths the tax cost.