The Roth vs Traditional question reduces to one number: will your tax rate be higher now or in retirement? Enter your annual contribution, current and expected retirement brackets, and this calculator shows the after-tax value of both accounts at retirement — the winner and the exact dollar difference.
How this calculator works
Both accounts get the same gross budget. Traditional: the full contribution compounds tax-deferred (FV = C/12 × ((1+i)^n − 1)/i monthly), then every dollar is taxed at your retirement rate — after-tax = FV × (1 − retirement rate). Roth: you pay tax now, so only C × (1 − current rate) enters the account, but qualified withdrawals are entirely tax-free. Same growth multiplier, so the winner depends only on the bracket comparison — equal rates produce (almost) equal results.
Scenario examples (2026 rates)
| Annual contribution ($) | Roth IRA — tax-free at retirement | Traditional IRA — after tax at withdrawal |
|---|
| 3,500 | $277,543.4 | $277,543.4 |
| 5,250 | $416,315.1 | $416,315.1 |
| 7,000 | $555,086.8 | $555,086.8 |
| 10,500 | $832,630.2 | $832,630.2 |
| 14,000 | $1,110,173.61 | $1,110,173.61 |
Every number above is computed by the same in-browser engine as the calculator — nothing is hardcoded.
Why the Bracket Comparison Decides Everything
Strip away the marketing and both accounts run the identical compounding engine; the only difference is when the IRS takes its share. A Traditional IRA contribution avoids tax today and pays it on the way out, so its after-tax value equals the future value times one minus your retirement rate. A Roth contribution pays tax first, then grows untouched, so its after-tax value equals the future value of the smaller after-tax deposit. Because both share the same growth multiplier, the winner is determined solely by which rate is higher: the one you pay now or the one you pay later. When they are equal the accounts finish within rounding of each other, which this calculator shows as a tie. That is a real result, not a bug, and it is why any advisor who says one account is always better is selling something. The practical work is estimating your future marginal rate honestly, including Social Security, pensions, part-time work and required minimum distributions that most retirees forget to count.
Estimating Your Retirement Bracket Without Guessing
The retirement rate field is the one input people fudge, and it decides the answer. Build it from expected annual retirement income rather than from feelings. Start with Social Security, up to 85 percent of which is taxable for most retirees, then add pensions, rental income and planned withdrawals from other pre-tax accounts. In 2026 a married couple filing jointly pays 12 percent up to about $100,800 of taxable income and 22 percent above it, so a couple with $70,000 of combined Social Security and pension income has little room left in the 12 percent bracket before 401(k) withdrawals begin. Required minimum distributions from age 73 force those withdrawals whether you need the cash or not, which is precisely why large pre-tax balances often push retirees into a higher bracket than they had while working. Run this calculator at three retirement rates, 12, 22 and 32 percent, to see the full range before committing.
When Each Account Wins in Real Life
Early-career savers in the 10 or 12 percent bracket almost always favor Roth: they pay tax at the lowest rates of their lives and lock in decades of tax-free growth, and if the scheduled post-2025 bracket creep raises future rates, today is the cheapest tax they will ever pay. Peak earners in the 32 or 37 percent brackets who expect a quieter retirement usually favor Traditional: the deduction is captured at a top rate and the withdrawals land in a middle one. Planners relocating from a high-tax state to a tax-free one lean Traditional for the same asymmetry. Two non-tax tiebreakers matter too. Roth IRAs have no required minimum distributions during the owner lifetime and pass to heirs income-tax-free, which is a genuine estate advantage. Traditional IRAs offer limited creditor protection that varies by state and allow penalty-free withdrawals for some early-retirement situations through substantially equal periodic payments. If the calculator shows the two accounts within a few thousand dollars of each other, split the contribution and buy flexibility instead of chasing a rounding error.