Updated June 20, 2026
Planning for retirement?
See how your full retirement portfolio grows over time with the Retirement Investment Calculator, or model total portfolio growth with the Investment Calculator.
How a Roth conversion works
A Roth conversion moves money from a traditional IRA (or pre-tax 401k) into a Roth IRA. You pay ordinary income tax on the converted amount in the year of conversion. After that, the money grows tax-free and qualified withdrawals in retirement are also tax-free.
The IRS treats the converted amount as ordinary income in the year you convert. If you convert $50,000 and your marginal federal rate is 22 percent, you owe $11,000 in federal tax on the conversion. State income taxes may apply on top of that, depending on where you live. The official rules are in IRS.gov's Roth conversion FAQ.
What the calculator computes
| Output | How it is calculated |
|---|---|
| Tax cost to convert now | Converted amount x current marginal rate |
| Roth value after N years | Full converted amount grown at the annual return (no tax on withdrawal) |
| Traditional IRA before-tax value | Same amount grown at the same return (tax deferred) |
| Traditional IRA after-tax value | Before-tax value x (1 minus future tax rate) |
| Roth advantage | Roth value minus traditional after-tax value (positive = Roth wins) |
Both accounts grow the same pre-tax amount at the same assumed return. The only variable is when the tax is paid: now at the current rate (Roth) versus later at the future rate (traditional).
When a Roth conversion makes sense
A Roth conversion is worth it if your tax rate at withdrawal will be higher than your rate at conversion. Common scenarios where that happens: you are in a temporarily low-income year, tax rates rise broadly, or your retirement income (Social Security, pensions, RMDs from other accounts) pushes you into a higher bracket than you expect.
Roth IRAs have no required minimum distributions during the account owner's lifetime, as stated on IRS.gov. That makes them useful for people who do not need the money in retirement and want to pass assets to heirs, because the balance keeps compounding without forced annual withdrawals starting at age 73.
Common Roth conversion strategies
Many people convert just enough each year to fill up their current tax bracket without crossing into the next one. Others target years when income drops, such as early retirement before Social Security begins, or a year with large deductions. Converting in smaller amounts over several years, sometimes called a ladder or multi-year Roth conversion strategy, can limit the tax hit in any single year while still moving the balance across over time.
What this calculator does not cover
This tool uses a single federal marginal rate and a fixed annual return. It does not model state income taxes, the Medicare surcharge on higher incomes (IRMAA), Social Security taxation thresholds, or year-by-year portfolio volatility. The result is a planning estimate, not a guarantee. A tax professional or fee-only financial planner can model the full picture for your situation.
This tool is informational and educational only. It is not financial, tax, or legal advice. Tax law can change. Consult a qualified tax professional before making conversion decisions. Investing involves risk, including possible loss of principal.
A reformed credit analyst, Jessica Martinez turns dense financial paperwork into something you can actually use. She writes the explainers behind these calculators and checks every formula against a primary source before it ships.