IRA Calculator: Traditional or Roth, and What Each One Leaves You
An IRA calculator compares two versions of the same retirement account and shows why the choice between them is really a bet on tax rates. A traditional IRA gives you a tax break now and taxes withdrawals later. A Roth IRA taxes contributions now and lets qualified withdrawals out tax free. Put the same savings into each shape, run the same return, and the winner depends on the tax rate you pay today against the rate you expect in retirement.
That comparison trips up a lot of savers, because the traditional balance always looks bigger on the statement. It is bigger, and it should be: some of that balance belongs to the tax authority, not to you. The calculator strips that out by showing an after-tax balance for each version, which is the only fair way to compare them.
Traditional and Roth, side by side
A traditional IRA is funded with pre-tax money. Contributions may be deductible, growth is tax-deferred, and every dollar withdrawn in retirement is taxed as ordinary income. A Roth IRA is funded with after-tax money. You get no deduction now, growth is tax free, and qualified withdrawals in retirement are tax free too. Both share the same yearly contribution limit, $7,500 for 2026 for savers under 50, with an extra $1,100 catch-up from age 50 under the figures circulating for that year, and the limit covers all your IRAs combined.
The simple rule falls out of that setup. If your tax rate in retirement will be lower than your rate now, the traditional IRA usually wins, because you deduct at the high rate and pay at the low one. If your retirement rate will be higher, the Roth usually wins, because you pay at the low rate now and nothing later. If the rates are equal, the two come out close, and the Roth often edges ahead in this calculator's model because its starting balance is counted in full.
Every input, explained
Current age. Your age now, which sets the start of the projection.
Retirement age. The age you stop contributing. The gap between the ages is the compounding runway.
Current balance. What is already in the IRA. The calculator grows it at the assumed return for the full period.
Annual contribution (pre-tax $). The yearly amount added before tax, in traditional terms. For the Roth comparison, the calculator reduces this by your current tax rate, because Roth money goes in after tax.
Expected return (%/yr). The average yearly growth assumed. Real returns vary year to year, so treat this as a long-run average.
Tax rate now (%). Your current marginal rate, the rate on your last dollar of income. It sets both the traditional deduction value and the Roth contribution haircut.
Tax rate retired (%). The rate you expect to pay on withdrawals in retirement. This is a guess, and it is the guess the whole comparison turns on.
A worked example: $7,000 a year from 30 to 65
Take a saver who starts at 30 with $10,000, contributes $7,000 a year, earns a 7% average return, and retires at 65, giving 35 years of growth. Set the tax rate now at 22% and the retired rate at 15%. The calculator grows the balance year by year, adding each year's contribution after that year's growth.
- What you put in. $7,000 a year for 35 years totals $245,000 of contributions, plus the $10,000 starting balance.
- The traditional balance. Growing $10,000 plus $7,000 a year at 7% for 35 years gives a gross balance of $1,074,423.96. Growth supplied $819,423.96 of that total.
- The traditional tax bill. Tax at 15% on the whole gross balance is $161,163.59, leaving an after-tax balance of $913,260.37.
- The Roth balance. Roth contributions go in after 22% tax, so only $5,460 a year is invested. Growing that at 7% for 35 years gives $861,539.17, all of it yours, with no tax left to pay on qualified withdrawals.
- The verdict. Traditional wins here by $51,721.20, because you deducted at 22% and paid at 15%. The 7-point rate gap, applied to a seven-figure balance, is worth more than the Roth's tax-free growth.
Milestones show the same late surge as every long compounding story. The traditional gross balance reaches $116,386.65 by age 40, $325,665.29 by age 50, and $1,074,423.96 by age 65. More than two thirds of the final balance arrives in the last 15 years. Starting late does not just shorten the runway, it cuts off the steepest part of the curve.
When the winner flips
Change only the tax rates and the verdict changes, which is exactly why the calculator asks for both. The table below holds the savings plan fixed and varies the rates.
| Tax now / retired | Traditional after tax | Roth after tax | Winner |
|---|---|---|---|
| 22% / 15% | $913,260.37 | $861,539.17 | Traditional by $51,721.20 |
| 22% / 22% | $838,050.69 | $861,539.17 | Roth by $23,488.48 |
| 12% / 22% | $838,050.69 | $958,304.99 | Roth by $120,254.29 |
| 32% / 15% | $913,260.37 | $764,773.36 | Traditional by $148,487.01 |
The pattern is clean. A falling rate favors traditional, a rising rate favors Roth, and the wider the gap, the bigger the prize. Early-career savers in a low bracket often do well with Roth contributions, since they pay little tax now. Peak earners near retirement often do well with traditional deductions, since they shelter income at their highest rate. Many savers end up holding both, which hedges the one thing nobody can know: future tax law.
Return assumptions matter almost as much as tax rates. At 5% instead of 7%, the traditional gross balance falls to $687,402.31. At 9% it rises to $1,714,114.96. Test your numbers at a return a couple of points below your optimistic guess before you rely on them.
Common mistakes
- Comparing gross balances. A $1,074,423.96 traditional balance against an $861,539.17 Roth balance is not a traditional win until tax is taken out. Compare after-tax balances only.
- Forgetting the combined limit. The yearly limit covers traditional and Roth contributions together. You cannot put the full limit into each one in the same year.
- Ignoring required minimum distributions. Traditional IRAs force withdrawals from age 73 or 75 depending on birth year, while Roth IRAs have no lifetime required withdrawals for the owner. That flexibility has real value in retirement planning.
- Withdrawing before 59 and a half. Early withdrawals from a traditional IRA usually face income tax plus a 10% penalty, with limited exceptions. Roth contributions, but not their earnings, can come out earlier without penalty.
Practical tips
If you are unsure which shape to pick, start with the rate test in the table above, then consider splitting contributions between the two. Contribute early in the year when you can, keep the contribution automatic, and revisit the choice when your income jumps or falls sharply, because a promotion or a career break can flip the winning shape overnight.
Frequently asked questions
Is a traditional IRA or a Roth IRA better for me?
It turns on tax rates. In our example at 22% now and 15% retired, traditional wins by $51,721.20. At 12% now and 22% retired, Roth wins by $120,254.29. Run your own rates through the calculator rather than copying someone else's answer.
How much can I contribute to an IRA in a year?
The limit for 2026 is $7,500 if you are under 50, plus a catch-up amount from age 50, and it covers all your traditional and Roth IRAs combined. You also need earned income at least equal to your contribution, and Roth eligibility phases out at higher incomes.
Why does the Roth balance look smaller before tax is counted?
Because Roth contributions go in after tax. At a 22% rate, a $7,000 pre-tax contribution becomes $5,460 invested, so the Roth balance grows from smaller yearly inputs. After tax, the comparison is fair, and in our example the Roth keeps the full $861,539.17.
Can I have both a traditional IRA and a Roth IRA?
Yes, and many savers do. The yearly limit applies to the total across both, not to each one separately. Holding both gives you taxable and tax-free money in retirement, which lets you manage your yearly tax bill by choosing which pot to draw from.
When must I start withdrawing from a traditional IRA?
Required minimum distributions begin at age 73 or 75 depending on your birth year, and the withdrawn amount is taxed as income. Roth IRAs have no required withdrawals for the original owner, which is one reason they suit savers who want to leave money invested longer.
Related calculators: 401(k) Calculator, Pension Calculator, and Social Security Calculator.
The IRA decision looks complicated from the outside and simple once you see it clearly: guess your tax rate now, guess it in retirement, and let the lower rate decide where the money goes. Get that guess roughly right and either shape will serve you well, as long as the contributions actually happen every year.
Disclaimer: this guide explains IRA math for education only and is not financial, tax, or investment advice. Contribution limits, deductibility, Roth eligibility, and required distribution ages depend on current law and your personal situation, so confirm the details with the IRS or a tax professional before contributing.
Further reading: the IRS sets out the rules for both IRA types, including limits and eligibility, on its individual retirement arrangements page, which is the right place to check the current year's figures.