A Roth vs. Traditional IRA calculator should answer a simple question: under the assumptions you enter, which tax treatment leaves you with more spendable money later? The part most calculators gloss over is that the answer can change when a Traditional IRA contribution is not deductible—or when you compare the same IRA contribution without accounting for the tax savings a deductible Traditional IRA can create today.
So don’t read the result as “Roth is better” or “Traditional is better.” Read it as: these are the assumptions making one path look better in this scenario. That’s a much more useful answer.
Show the quick answer
- The core trade-off: Roth IRA contributions do not create a current tax deduction, but qualified withdrawals can be tax-free. A deductible Traditional IRA can reduce current taxable income, while taxable withdrawals come later.
- 2026 contribution limit: Your combined Traditional and Roth IRA contributions are generally limited to $7,500 for 2026, or $8,600 if you're age 50 or older, subject to taxable-compensation rules.
- The hidden assumption: Putting the same dollar amount into each IRA is not always an equal-cost comparison. A deductible Traditional contribution can create current tax savings; ignoring what happens to those savings can tilt the math toward Roth.
- Eligibility still matters: 2026 Roth contribution limits and Traditional IRA deduction phase-outs depend on modified AGI, filing status, and workplace-plan coverage. The calculator screens for these rules before treating the comparison as personally applicable.
- What the tool does not model: Backdoor Roth conversions, pro-rata taxation, nondeductible IRA basis, RMD strategy, IRMAA, ACA subsidies, and future tax-law changes need separate analysis.
On This Page
- Roth vs. Traditional IRA Calculator
- How to Read the Roth vs. Traditional IRA Calculator Result
- The Tax-Rate Rule That Drives Most Roth vs. Traditional IRA Comparisons
- Why Equal IRA Contributions Can Be a Misleading Comparison
- 2026 IRA Contribution, Roth Income and Traditional Deduction Rules
- Your Next IRA Question
- Roth vs. Traditional IRA: What Actually Changes?
- When a Roth vs. Traditional IRA Calculator Can Mislead You
- Roth vs. Traditional IRA Calculator FAQ
- Bottom Line: Use the Calculator to Find the Assumption That Matters
- How We Verified This
Roth vs. Traditional IRA Calculator
Compare the tax timing, not just the ending balance. This model shows what happens under your assumptions and flags when Roth eligibility or Traditional IRA deductibility may change the comparison.
Comparison result
How to Read the Roth vs. Traditional IRA Calculator Result
The calculator starts with the same annual IRA contribution and growth assumption for both accounts. For the Roth path, it assumes the eventual withdrawal is qualified and therefore tax-free. For the Traditional IRA, it applies the tax rate you enter to the modeled retirement value.
Then it does something the old version of this page did not handle well: if your Traditional IRA contribution appears fully deductible, it estimates the current tax reduction and gives you the option to model reinvesting that tax savings in a taxable side account. That keeps the tax benefit from vanishing from the comparison as if you never received it.
Michael’s rule: Don’t ask “Which IRA wins?” until you know what the calculator assumed happened to the Traditional IRA tax savings. That one detail can flip the story the numbers appear to tell.
The result is still a scenario, not a recommendation. If a few percentage points of assumed retirement tax rate change the answer, that is useful information: your decision is sensitive to an unknowable future input. In that case, tax diversification or testing several scenarios may be more useful than pretending the calculator found a permanent winner.
The Tax-Rate Rule That Drives Most Roth vs. Traditional IRA Comparisons
At the simplest level, the Roth-versus-Traditional decision is about when you want to pay income tax.
- Roth IRA: you do not deduct the contribution now. If the eventual distribution is qualified, the withdrawal can be tax-free.
- Traditional IRA: the contribution may be deductible now. Deductible contributions and earnings are generally taxable when withdrawn.
The IRS describes those tax treatments directly in its current Traditional and Roth IRA guidance. The practical comparison is not “taxes versus no taxes.” It is your tax cost now versus the tax cost attached to future Traditional IRA withdrawals.
That sounds obvious, but there is a wrinkle I saw repeatedly in planning conversations: people compare today’s marginal tax rate with a vague idea that they’ll be “in the same bracket” in retirement. Retirement income does not arrive as one giant block taxed at one rate. Taxable income fills brackets from the bottom up, and deductions, Social Security taxation, pensions, RMDs, Roth withdrawals and other income can all change the mix.
That is why this tool asks you for an estimated tax rate on the Traditional withdrawals rather than pretending your current salary automatically tells us your future tax bill. Run more than one retirement-tax scenario if you’re unsure. A calculator is much better at showing sensitivity than predicting Congress and your retirement income 30 years from now.
Why Equal IRA Contributions Can Be a Misleading Comparison
Suppose you put $7,500 into a Roth IRA and $7,500 into a fully deductible Traditional IRA. The account contributions are equal. The current economic cost may not be.
If a deductible Traditional contribution saves tax at a 24% combined marginal rate, a $7,500 contribution could create roughly $1,800 of current tax reduction. If that $1,800 is spent, the Roth and Traditional paths are being funded with different current resources. If it is invested, that side account becomes part of the Traditional strategy’s economic result.
This is why the calculator lets you model reinvesting the Traditional tax savings. It is still simplified—the taxable side account has its own assumptions—but it prevents the biggest apples-to-oranges mistake: comparing two identical IRA balances while quietly throwing away one account’s current tax benefit.
There is a second wrinkle at the contribution limit. If you can afford to max out either IRA, a maxed Roth effectively places more after-tax value inside the tax-advantaged account because the tax has already been paid outside it. That can matter, too. There is no one-line rule that makes the same account type optimal for every saver.
2026 IRA Contribution, Roth Income and Traditional Deduction Rules
For 2026, the total you contribute across all of your Traditional IRAs and Roth IRAs is generally limited to $7,500, or $8,600 if you’re age 50 or older, or your taxable compensation if that is lower. That is a combined limit—not $7,500 for a Roth plus another $7,500 for a Traditional IRA. 1
The IRS also applies separate income rules to Roth contribution eligibility and Traditional IRA deductibility. Those are two different gates. You can generally contribute to a Traditional IRA regardless of income if you otherwise qualify, but the contribution may not be deductible. Direct Roth contributions can be reduced or blocked by modified AGI. See my 2026 Roth IRA contribution guide if you need the Roth eligibility calculation itself.
| 2026 rule | Single / head of household | Married filing jointly |
|---|---|---|
| Direct Roth contribution phase-out | $153,000–$168,000 modified AGI | $242,000–$252,000 modified AGI |
| Traditional IRA deduction phase-out if contributor is covered at work | $81,000–$91,000 modified AGI | $129,000–$149,000 modified AGI |
| Traditional deduction phase-out if contributor is not covered but spouse is | Not applicable | $242,000–$252,000 modified AGI |
Married-filing-separately rules can be much tighter, and whether you lived with your spouse during the year matters. The current thresholds above come from the IRS’s Publication 590-A and 2026 retirement-limit guidance. 2
The practical check: before trusting a Traditional IRA “tax savings” result, verify that you actually get the deduction. A nondeductible Traditional IRA is not the same calculation with a smaller deduction—it creates basis and different tax reporting.
Roth vs. Traditional IRA: What Actually Changes?
| Question | Roth IRA | Traditional IRA |
|---|---|---|
| Current-year deduction? | No deduction for a regular Roth IRA contribution. | May be fully deductible, partly deductible or nondeductible depending on modified AGI and workplace-plan coverage. |
| Income can limit the contribution? | Yes. Direct contributions phase out at higher modified AGI. | Income does not by itself prevent a regular contribution, but it can limit the deduction. |
| Tax on retirement withdrawals? | Qualified distributions are tax-free. | Deductible contributions and earnings are generally taxable; nondeductible basis changes the calculation. |
| Lifetime RMD for original owner? | No. | Yes, generally beginning under the applicable RMD-age rules. |
| Main calculator uncertainty | Future value of paying tax now and preserving a tax-free bucket. | Whether today’s deduction and future withdrawal tax rate produce a better after-tax trade-off. |
The IRS confirms that qualified Roth IRA distributions can be tax-free, while deductible Traditional IRA contributions and earnings are generally taxable when withdrawn. It also says original Roth IRA owners do not have lifetime RMDs, while Traditional IRAs are generally subject to RMD rules. 3
When a Roth vs. Traditional IRA Calculator Can Mislead You
The most dangerous calculator is not one that makes an arithmetic mistake. It is one that answers the wrong version of your question with great-looking precision.
1. Your Traditional IRA contribution is not fully deductible
If the deduction is limited, the clean “deduct now, pay tax later” model breaks. Nondeductible Traditional IRA contributions create basis, generally require Form 8606 tracking, and can make future distributions partly taxable rather than fully taxable. The rebuilt calculator flags this instead of inventing a deduction you may not receive.
2. You’re really asking about a backdoor Roth
A backdoor Roth is a contribution-and-conversion process, not a third type of IRA. Existing pre-tax Traditional, SEP or SIMPLE IRA balances can affect the taxable portion of a conversion through the pro-rata rules. That is outside this calculator’s Page Job. Use the dedicated conversion guidance rather than forcing a conversion question into a contribution calculator.
3. You treat one retirement tax rate as a prediction
Your retirement tax picture can change with pensions, Social Security, withdrawals, RMDs, Roth conversions, deductions, filing status and future law. Instead of arguing over one “correct” future rate, run a low, middle and high scenario. If the result keeps pointing the same way, the model is more robust. If it flips easily, that sensitivity is the answer.
4. Another tax threshold matters more than the IRA alone
Retirement withdrawals can interact with other parts of the tax system. Medicare IRMAA, ACA premium-tax-credit rules, Social Security taxation and capital-gain brackets are examples of issues a simple IRA contribution calculator does not model. Those do not make this tool useless; they tell you where its boundary is.
Roth vs. Traditional IRA Calculator FAQ
Can I contribute to both a Roth IRA and a Traditional IRA in 2026?
Yes, if you otherwise qualify—but the $7,500 annual limit ($8,600 if age 50+) generally applies to your combined regular contributions across both types, not separately to each account. If your taxable compensation is lower, that lower amount can control instead.
Is a Roth IRA always better when you’re young?
No. A younger saver often has more years for tax-free Roth growth, and early-career income can mean a relatively low current tax rate. But age by itself does not decide the tax trade-off. Current marginal rate, future taxable income, Traditional deduction eligibility, contribution limits and what happens to the tax savings all matter.
At what age is a Roth IRA no longer worth it?
There is no universal cutoff age. A short time horizon can reduce the impact of compounding, but tax-rate differences, withdrawal flexibility, RMD exposure, estate goals and eligibility can still matter. “How old are you?” is an input; it is not a verdict.
What if my tax rate is the same now and in retirement?
If the relevant tax rates truly are the same and the comparison uses the same pre-tax economic resources, Roth and deductible Traditional treatment can be mathematically similar. In the real world, contribution limits, whether tax savings are reinvested, deductions, taxable-account drag and the way retirement income fills tax brackets can break that neat equivalence. That is exactly why the calculator exposes the tax-savings assumption instead of hiding it.
What if I can contribute to a Traditional IRA but cannot deduct it?
Then this page’s fully deductible Traditional comparison is not the right personal model. A nondeductible Traditional IRA creates after-tax basis and different distribution-tax rules. It can also matter in a later Roth conversion. The calculator flags that condition rather than presenting the deductible result as though nothing changed.
Bottom Line: Use the Calculator to Find the Assumption That Matters
The useful question is not “Which IRA is best?” It is: Which tax treatment fits the tax rates and rules I’m actually comparing?
Run the calculator once with your best estimate. Then change the retirement tax rate. Toggle the Traditional tax-savings reinvestment. Check the 2026 eligibility screen. If a small assumption change flips the result, don’t fight the calculator for certainty it cannot provide. You just learned that the decision is sensitive—and that is valuable planning information.
One thing I’ve learned: the best calculator result is often not the bigger number. It’s discovering which assumption you need to get right before the number deserves your trust.
How We Verified This
The 2026 limits and tax-treatment statements on this page were checked against current IRS guidance.
