When your rates are equal, both options produce identical results. The rate difference is the only thing that matters.
| Retire rate | Roth | Traditional | Better |
|---|
What this doesn’t model
State taxes are ignored. Some states exempt retirement account distributions; others don’t. If your state taxes Traditional IRA withdrawals but not Roth distributions, Roth may have an additional edge not shown here.
Contribution limits are not binding here. In practice, Roth and Traditional contributions share the same annual dollar limit. Because Roth uses after-tax dollars, funding the same limit costs more out of pocket — meaning you’re effectively sheltering more money. This is the one case where Roth wins even when the tax rates are equal: if you can max out either account, Roth shelters more real wealth.
This model assumes no differences in contribution mechanics. Employer match rules, plan availability, income limits on Roth contributions, and conversion rules are not modeled.
Already retired and thinking about Roth conversions? See the Roth Conversion Calculator — it models IRMAA surcharges, bracket-fill strategies, and the widow’s penalty.
Educational only. Consult a tax professional before making contribution decisions. Tax law can change; these calculations use fixed current-year rates.
Educational purposes only. This calculator illustrates mathematical concepts related to long-term investing and is not financial advice. Past market returns do not guarantee future results. Portfolios can lose value. The formulas assume constant returns and do not account for taxes, fees, inflation, or sequence-of-returns risk. Consult a qualified financial professional before making investment decisions.