Roth Conversion Calculator

Updated October 2026

A Roth conversion moves money from a traditional IRA or 401(k) into a Roth IRA. You pay income tax on the converted amount now, and in exchange the money grows tax-free and comes out tax-free later. Whether that's a good trade comes down mostly to one comparison: your tax rate today versus your tax rate when you would otherwise withdraw the money. This calculator makes that comparison side by side. With the defaults, converting $100,000 at a 24% rate costs $24,000 in tax now. If your rate in retirement would be 22%, not converting comes out $7,739 ahead after 20 years; at 32% in retirement, converting wins by $30,957.

How the comparison works

To compare fairly, both paths start with the same money. In one, you convert and pay the tax from savings, so the full amount grows in the Roth. In the other, you leave the IRA alone and keep that tax money invested. After the growth period, the IRA is taxed at your retirement rate when withdrawn. The result:

$100,000 converted, 7% annual growth, tax paid from savings.

When the rates are equal, the two paths come out the same. Everything else is about whether your future rate will be higher or lower than today's.

When converting tends to make sense

• Low-income years. Early retirement before Social Security and RMDs start, a sabbatical, or a year between jobs can put you in the 10% or 12% bracket. Those are prime conversion years.
• Large traditional balances. Big IRAs lead to big required minimum distributions starting at 73 (75 for those born in 1960 or later), which can push you into higher brackets and Medicare surcharges later.
• Leaving money to heirs. Most non-spouse heirs must empty an inherited IRA within 10 years. An inherited Roth follows the same timeline but comes out tax-free, which helps heirs in their peak earning years.
• You can pay the tax from outside the IRA. Paying it from the converted money shrinks what goes into the Roth and, before 59½, the withheld amount can be penalized.

When to hold off

• You expect a lower tax rate in retirement than now.
• The conversion would push you into a much higher bracket. Converting in smaller pieces over several years often avoids that.
• You are within two years of Medicare. The added income can raise your premiums through IRMAA two years later; check the IRMAA calculator.
• You rely on income-based benefits such as ACA health insurance subsidies, which the extra income can reduce.

Rules to know

• There is no income limit on conversions.
• Conversions can no longer be undone (recharacterized). Since 2018, a conversion is final.
• Each conversion has its own five-year clock for penalty-free withdrawal of the converted amount if you are under 59½.
• Roth IRAs have no required minimum distributions for the original owner.

To plan conversions over several years rather than one amount, try the Roth conversion optimizer. To see your current bracket, use the tax bracket calculator.

Frequently asked questions

The comparison assumes the conversion tax is paid from savings and that money otherwise stays invested at the same return, with taxes on its growth ignored (which slightly favors not converting). Rules from the IRS (Publication 590-A and 590-B). Not tax advice.