ReckonBoxRoth or traditional, compared honestly
A Roth versus traditional IRA calculator should compare the two accounts at equal cost, which means investing the tax deduction the traditional IRA gives you. Skip that step, as most do, and the comparison quietly tilts toward the Roth every time.
On $7,000 a year for 30 years at 7%, both accounts grow to the same $661,226. The Roth is yours tax-free. The traditional is taxed on the way out, but the deduction it gave you along the way, invested, is worth $158,694. Count that and the traditional finishes ahead by $13,225, because your rate now is higher than your rate later.
The comparison the field rigs
Most Roth versus traditional calculators compare the same contribution in each account without investing the traditional deduction, which is not an equal-cost comparison. It makes the Roth look far better than it is.
calculator.net and NerdWallet both compare a Roth against a plain taxable account, not a traditional one at all. The trap is subtle. Contributing $7,000 to a Roth costs $7,000 of take-home pay. Contributing $7,000 to a traditional costs less, because the deduction hands some of it back. Ignore that refund and the traditional looks worth just $515,756 against the Roth's $661,226, a $145,000 gap that vanishes the moment you treat the two fairly.
What actually decides it
Once the deduction is invested, the winner comes down to one thing: whether your tax rate is higher now or in retirement. Everything else cancels out.
Pay tax now at a high rate to fund a Roth, and you lose if your retirement rate turns out lower. Take the deduction now at a high rate and pay later at a lower one, and the traditional wins. When the two rates match, they tie to the dollar, and the decision moves to other things, like the Roth having no required minimum distributions:
| $7,000/year, 30 years, 7% return | After tax at retirement |
|---|---|
| Roth | $661,226 |
| Traditional, deduction invested (fair) | $674,450 |
| Traditional, deduction spent (the naive view) | $515,756 |
Where the numbers come from
Both accounts grow the same contribution at the same return, so the pre-tax balance is identical. The Roth balance is the after-tax result, since you already paid tax going in. The traditional balance is reduced by your retirement tax rate on withdrawal, then the deduction, worth your contribution times your current rate each year, is grown at the same return and added back. That side fund is what makes the cost equal.
The model assumes the deduction is invested in a tax-advantaged way and that both rates hold steady, which real tax brackets do not. For 2026, per the IRS, the IRA limit is $7,500, or $8,600 at age 50 or older, and Roth eligibility phases out over a modified gross income range of $153,000 to $168,000 single and $242,000 to $252,000 married filing jointly.
What this does not decide for you
This weighs the tax math, not the whole choice. It does not model required minimum distributions, which a Roth IRA avoids and a traditional does not, the estate benefit of tax-free Roth dollars, or the chance that tax law changes before you retire. A Roth also gives certainty, since you have already settled with the IRS.
None of this is advice on which account to open. It shows the honest tax comparison so you can weigh it against your own view of future rates. For a decision that turns on your full tax picture, a CPA or a licensed financial adviser is the right call.
Frequently asked questions
Is a Roth or traditional IRA better? It depends almost entirely on whether your tax rate is higher now or in retirement, once you invest the traditional IRA tax deduction for a fair comparison. On $7,000 a year for 30 years at 7%, with a 24% rate now and 22% later, the traditional wins by about $13,225. Flip the rates and the Roth wins, because you would rather pay tax at the lower rate.
Why do most Roth vs traditional calculators favor the Roth? Because they compare the same contribution in each account without investing the traditional IRA tax deduction. That is not equal-cost. On the default inputs, ignoring the deduction makes the traditional look worth just $515,756 against the Roth $661,226, a $145,000 gap, when the fair comparison actually has the traditional ahead by $13,225.
What is the equal-cost comparison? The equal-cost comparison recognizes that a $7,000 traditional contribution generates a tax deduction worth $1,680 at a 24% rate, which invested at the same return grows to $158,694 over 30 years. Adding that to the taxed traditional account makes the two IRAs comparable, since the Roth used post-tax dollars from the start.
What is the 2026 IRA contribution limit? For 2026, per the IRS, the IRA contribution limit is $7,500, or $8,600 if you are age 50 or older, across your Roth and traditional IRAs combined. Roth contributions phase out over a modified adjusted gross income range of $153,000 to $168,000 for single filers and $242,000 to $252,000 for married couples filing jointly.
When do Roth and traditional IRAs tie? They tie when your tax rate is the same now as in retirement, once the traditional deduction is invested. In that case both reach the same after-tax value, and the choice rests on other factors: a Roth has no required minimum distributions and no tax on withdrawals, while a traditional lowers your taxable income today.
Does this tool account for the tax deduction on a traditional IRA? Yes, and that is the whole point. It invests the annual deduction, worth your contribution times your current tax rate, at the same return, then adds it to the after-tax traditional account. Most calculators skip this, which is why they overstate the Roth advantage. The tool shows both the fair and the naive figures side by side.