A Roth conversion means moving money from a Traditional IRA or 401(k) into a Roth account, paying ordinary income tax on the converted amount in the year you do it. The question that actually matters isn’t “should I convert” in the abstract — it’s whether the tax rate you’d pay today is lower than the rate you’d likely pay on that same money later.
This calculator does that comparison. Enter the amount you’re considering converting and your best estimate of your tax rate now versus in retirement, and it shows the tax cost each way.
Should You Convert to Roth?
Enter the amount you’re considering converting and your tax rate estimates.
This assumes similar investment growth either way, so the comparison comes down to the tax-rate difference alone. It doesn’t account for how the conversion might affect your Medicare IRMAA bracket or other income-based thresholds in the conversion year.
A Few Things This Roth Conversion Calculator Doesn’t Cover
This tool compares tax rates only — it’s a starting point, not a complete answer. A few real factors it leaves out:
The five-year rule. Converted funds need to sit in the Roth for five years (or until you turn 59½, whichever comes first) before you can withdraw the converted amount penalty-free. If you’re converting close to when you expect to need the money, that timing matters as much as the tax math.
Paying the tax bill. The math above only works if you can pay the conversion tax with money from outside the account. Pulling the tax bill from inside the IRA shrinks the amount that grows tax-free and changes the numbers.
Medicare premiums. A large conversion counts as taxable income in the year you do it, and could push you into a higher IRMAA bracket two years later. Check your number with the IRMAA Calculator before converting a large amount in one year.
Permanence. Roth conversions have been permanent since 2018 — there’s no undoing one. That’s why spreading conversions across multiple smaller years, rather than one large one, is usually the safer approach.
For the full breakdown of how Roth and Traditional accounts differ, and which one tends to make more sense for different situations, see my Roth vs. Traditional IRA guide. And if you’re already required to draw down a Traditional account, the RMD Calculator shows what the IRS requires each year.
This isn’t tax advice. The right choice depends on your specific income, tax bracket, and timeline — a tax professional or fee-only financial advisor can run the actual numbers for your situation.