HenryCalc
Roth conversion calculator
Estimate the marginal federal tax cost of converting traditional retirement money to Roth.
What a Roth conversion costs
Converting traditional retirement money to Roth means paying income tax now so that all future growth and withdrawals are tax-free. The converted amount stacks on top of your other income for the year, so its cost is the marginal tax it adds - not your average rate. Convert too much in one year and you push yourself into a higher bracket.
What this calculator estimates
Enter the amount you want to convert, your other taxable income, and your filing status. The tool computes your tax before and after the conversion and shows the difference - the true cost - plus the effective rate on the converted dollars.
Bracket-filling strategy
The smartest conversions happen in low-income years: early retirement before required minimum distributions and Social Security begin, a gap year, or a year with unusually low income. The goal is usually to convert just enough to fill a target bracket. Watch the effective rate as you raise the amount - when it jumps, you have crossed into the next bracket and may want to stop there and finish next year.
Frequently asked questions
- How is a Roth conversion taxed?
- The amount you convert from a traditional IRA or 401(k) is added to your ordinary income for the year and taxed at your marginal rate. There is no early-withdrawal penalty on a conversion, but you owe income tax on the pre-tax portion.
- When does a Roth conversion make sense?
- Conversions are most valuable in lower-income years - early retirement before Social Security and required distributions begin, a sabbatical, or a year with business losses - when your marginal rate is temporarily low.
- How much should I convert?
- A common strategy is to convert just enough to fill up a target tax bracket without spilling into the next one. The effective rate this calculator shows helps you find that ceiling.
Last reviewed January 2026. This calculator provides general educational estimates based on the inputs you enter and simplified assumptions. It is not financial, tax, legal or investment advice, and figures may differ from your actual liability. Verify with a licensed CPA or financial advisor before acting.