Compare a deductible Traditional IRA with a Roth IRA on the same slice of pay, using your tax rate now and the rate you expect in retirement
Enter the amount of pay you set aside each year before tax, how many years it grows, the return you want to assume, your tax rate today and the rate you expect when you withdraw. The calculator puts the same slice of pay into each account — a Roth after paying today's tax on it, a deductible Traditional IRA before tax — and shows what each is worth after tax in retirement. It's a comparison of tax treatment, not a prediction of returns.
Roth: you pay tax now, invest what's left, and qualified withdrawals are tax-free (IRS Publication 590-B). After-tax value = pay × (1 − tax rate now) × growth. Traditional (deductible): you invest the full amount, it grows, and withdrawals are taxed as ordinary income. After-tax value = pay × growth × (1 − tax rate in retirement). Growth is the same factor in both, so the account taxed at the lower rate wins, and equal rates give exactly the same result. Deductibility of Traditional IRA contributions depends on your income and whether you have a workplace plan (IRS Publication 590-A).
Setting aside $7,500 of pay a year for 30 years at an assumed 7%: in the 22% bracket the Roth gets $5,850 a year after tax and grows to $591,277, tax-free. The Traditional IRA gets the full $7,500, grows to $758,048, and if it is taxed at 12% in retirement you keep $667,082 — $75,805 more than the Roth. Reverse the rates (12% now, 22% later) and the Roth leaves $75,805 more. At 22% both times, both come to $591,277.
| Tax now / in retirement | Roth | Traditional | Leaves more |
|---|---|---|---|
| 22% / 12% | $591,277 | $667,082 | Traditional |
| 22% / 22% | $591,277 | $591,277 | Same |
| 12% / 22% | $667,082 | $591,277 | Roth |
| 24% / 24% | $576,116 | $576,116 | Same |
| 32% / 22% | $515,473 | $591,277 | Traditional |
Nobody knows future tax law, so treat the retirement rate as a range. Things that push it up: a large pre-tax balance, a pension, Social Security, required minimum distributions from Traditional accounts. Things that push it down: retiring with little other income, or moving to a state with no income tax. Many people hold both kinds of account so they can choose which to draw from each year. The 2026 contribution limit of $7,500 ($8,600 at 50+) applies to both types combined.
If your tax rate in retirement will be lower than today, a deductible Traditional IRA usually leaves more after tax; if it will be higher, a Roth does; if it's the same, they come out equal. The calculator shows the difference for your own rates.
Because multiplication doesn't care about order: pay × (1 − t) × growth equals pay × growth × (1 − t). With 22% both times, $7,500 a year for 30 years at 7% gives $591,277 either way.
Yes. It compares the same amount of pay. The Roth only gets what's left after today's tax ($5,850 from $7,500 at 22%), while the Traditional IRA gets the full amount because the contribution is deductible.
Yes, but the $7,500 limit for 2026 ($8,600 if 50 or older) is shared across all your IRAs. Roth eligibility phases out at higher incomes, and Traditional deductions can phase out if you have a workplace retirement plan.
Tax rules, limits and pay data change. Check the current figures with the primary source before acting on them.