Roth Conversion Calculator
Compare converting a traditional IRA to a Roth vs. leaving it alone. See the 2026 tax cost, break-even years and after-tax value, with a fair side-by-side that counts the cash you'd use for the tax.
Calculator
Key Takeaways
What You Should Know
- A Roth conversion wins mainly when your tax rate now is lower than your rate when the money comes out. If the two rates are equal, the result is close to a tie.
- The converted amount is taxed as ordinary income this year. Paying that tax from outside savings, not from the IRA, keeps more money growing tax-free.
- Watch the side effects of a large conversion: a higher bracket, Medicare IRMAA surcharges two years later (2026 thresholds $109,000 single / $218,000 joint), and lost ACA subsidies before 65.
How it works
Calculation methodology
Short answer: convert when the tax rate you pay on the conversion today is lower than the rate you’d pay on the same dollars later, and pay the tax from money outside the IRA. Converting $50,000 at 22% and growing it for 20 years at 7% leaves about $8,600 more after tax than not converting if your future rate is 24%. If both rates are 22%, the Roth edge falls to about $4,700, and it comes almost entirely from avoiding capital-gains tax on the outside cash.
The comparison the calculator makes
| $50,000 IRA, 20 years at 7%, tax paid from savings | Convert now | Don’t convert |
|---|---|---|
| Tax paid today (22%) | $11,000 | $0 |
| Account value after 20 years | $193,484 (Roth) | $193,484 (traditional) |
| Tax when withdrawn (24%) | $0 | −$46,436 |
| $11,000 kept invested in a taxable account instead | — | +$37,832 |
| After-tax value | $193,484 | $184,880 |
Many calculators leave out the last row. They compare a Roth funded with outside cash against a traditional IRA with no outside cash, which overstates the Roth advantage. This calculator counts it.
Fill-the-bracket planning with 2026 brackets
The usual strategy is to convert just enough each year to “fill” a bracket you consider cheap. Taxable income limits for 2026:
| Rate | Single | Married filing jointly |
|---|---|---|
| 10% | up to $12,400 | up to $24,800 |
| 12% | up to $50,400 | up to $100,800 |
| 22% | up to $105,700 | up to $211,400 |
| 24% | up to $201,775 | up to $403,550 |
| 32% | up to $256,225 | up to $512,450 |
Taxable income is after the standard deduction ($16,100 single, $32,200 joint in 2026). A retired couple with $92,200 of gross income ($60,000 taxable) has $40,800 of room in the 12% bracket and another $110,600 in the 22% bracket.
Side effects to check before converting
- Medicare IRMAA. Medicare premiums use your income from two years earlier. A conversion at 63 or later can raise Part B and D premiums once MAGI tops $109,000 (single) or $218,000 (joint) under 2026 thresholds. The standard Part B premium is $202.90 a month.
- ACA premium tax credits before 65. For 2026 coverage, subsidies end above 400% of the poverty line ($62,600 for one person, $84,600 for two), because the enhanced credits expired after 2025. A conversion can push you over that line.
- Social Security taxation. More income can make up to 85% of benefits taxable.
- State tax. Converting while living in a no-income-tax state, and withdrawing later, can save the state portion outright.
Early retirees: the Roth conversion ladder
People who retire before 59½ can convert a slice of a traditional IRA each year. Each slice can be withdrawn penalty-free five tax years later. The first five years have to be covered from taxable savings or Roth contributions. Combined with a low income in early retirement, this often lets conversions happen in the 10%–12% brackets. See How Much Do I Need to Retire at 55.
Enter your own amounts above. To see how conversions shrink future required distributions, try the RMD Calculator.
Questions
Frequently Asked Questions
Assumptions
What this example assumes
- The calculator applies a single marginal rate to the whole conversion. A large conversion can cross into the next bracket, so check the bracket table below.
- When tax is paid from outside funds, the ‘don’t convert’ path keeps that cash invested in a taxable account, with growth taxed once at 15% long-term capital gains.
- Same annual return for both paths; no state tax unless you include it in the rates; no IRMAA, ACA or Social Security taxation effects.
Sources
Data sources
These sources support the inputs and assumptions used by this calculator. They are not personalized financial advice.
- IRS — 2026 tax inflation adjustments
2026 federal brackets and standard deductions.
- IRS — 2026 retirement plan and IRA limits (IR-2025-111)
IRA limit $7,500 and Roth IRA income phase-out ranges for 2026.
- CMS — 2026 Medicare Part B premiums
Standard Part B premium of $202.90 and the first IRMAA threshold.