Roth vs Traditional IRA Conversion Calculator
Should you convert a traditional IRA to Roth? Compare the after-tax value of converting now versus staying traditional, based on your tax rates and time horizon.
Figures last verified: rules current as of 2026 — verify · 2026 rules
Roth comes out ahead at these assumptions — mainly because your retirement tax rate isn't lower than today's.
| Amount converted | $100,000 |
| Tax paid on conversion | $24,000 |
| Roth value at retirement | $320,713.55 |
| Traditional value at retirement | $308,706.01 |
| Side account (tax kept invested) | $58,549.44 |
A conversion adds the converted amount to this year's taxable income, which can push you into a higher bracket and affect Medicare (IRMAA) and ACA subsidies. This model assumes flat rates and a simple taxable side account. Not tax advice — a conversion is often best done with a professional.
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How this calculator works
Who this is for
Anyone with a traditional IRA (or old 401(k)) weighing a Roth conversion — paying tax now to lock in tax-free growth and withdrawals. It's one of the most powerful, and most misunderstood, retirement moves.
The core trade-off
A conversion is essentially a bet on tax rates. If your tax rate in retirement will be the same or higher than today's, converting now (and paying tax at today's lower rate) usually wins. If you expect a lower rate later, staying traditional and deferring the tax tends to be better.
The math is close to a wash when your current and future rates are equal — unless you can pay the conversion tax from outside funds.
Why paying tax from outside matters so much
If you pay the conversion tax from a separate savings account rather than the IRA, your entire balance keeps compounding tax-free inside the Roth — effectively squeezing more tax-advantaged money into the account. That single choice often makes the difference between a conversion that pays off and one that doesn't.
Caveats & data freshness
The converted amount is added to this year's income, which can bump your bracket and raise Medicare premiums (IRMAA) or reduce ACA subsidies. This calculator uses flat tax rates and a simplified side-account model, and tax rules change over time. Large conversions are usually worth planning with a tax professional.
Frequently asked questions
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This site is for educational purposes only and does not constitute financial advice.