Side-by-side comparison with growth curves — drag sliders to see which wins for you.
2026 401(k) contribution limit: $24,500 ($32,500 if age 50+; $8,000 catch-up). Roth contributions are post-tax; Traditional are pre-tax. Investment returns assumed at 7% nominal. This is for estimation only — consult a financial advisor.
This tool compares the after-tax value at retirement of a Traditional 401(k) and a Roth IRA by applying the same pre-tax annual contribution to both. The only difference is when you pay tax: Traditional defers it to withdrawal (taxed at your retirement bracket), Roth pays it upfront (taxed at your current bracket) so withdrawals come out tax-free. After N years at return r, Traditional nets roughly (1 − retirementRate) × growth while Roth nets (1 − currentRate) × growth, so the winner is whichever bracket is lower. With 2026 limits — $24,500 for a 401(k), $7,500 for an IRA, $8,000 catch-up at 50+ — the same dollars behave very differently depending on your marginal rate today versus in retirement.
Same pre-tax salary dollars, same 30-year growth at 7%. Traditional defers the tax to withdrawal; Roth collects it on the way in and lets the growth exit free.
Priya is 35, in the 24% federal bracket today, and expects to be in the 18% bracket at retirement. She can save the full 2026 401(k) limit of $24,500/year, contributing the same pre-tax amount to either a Traditional 401(k) or a Roth IRA for 30 years at 7%.
Traditional 401(k) contributions are pre-tax (lower taxes now), Roth IRA contributions are post-tax (tax-free withdrawals later). Enter your income and contribution to see which wins over 30 years.
FreeToolHub 401k vs Roth IRA Calculator is a free browser-based tool that compares retirement account outcomes over 30 years, no signup.
Which retirement account makes you richer in 30 years? Compare 401(k) vs Roth IRA side by side. Free, 2026 tax rates, no signup.
This calculator answers the classic retirement question with your actual numbers instead of generic advice: should dollars go into a traditional 401(k) tax-deferred, a Roth account taxed now, or both. You enter current age, retirement age, current tax bracket, expected bracket in retirement, contribution amount, employer match, and expected return. The engine projects both accounts over up to 40 years of compounding, applies the tax treatment honestly, traditional balances are taxed on withdrawal while Roth balances are already net, and shows the after-tax value of each path side by side, including what an employer match adds when the plan is traditional. The verdict panel names the winner and the annual after-tax difference so the choice is a number, not a vibe.
Early-career workers in low brackets use it to see why Roth contributions during the cheapest tax years of their life compound tax-free for decades. Mid-career professionals at peak brackets check whether the immediate deduction beats future tax-free growth. Employees whose employer match lands in a traditional 401(k) regardless of their own election finally see the blended after-tax picture instead of comparing pure Roth against pure traditional. Couples planning around a pension or Social Security that will fill low brackets in retirement use the retirement-bracket input to model it. Anyone within ten years of retiring also benefits, because the crossover point where traditional wins can shift late in the accumulation phase.
(1) Enter your age, planned retirement age, and the annual amount you can contribute. (2) Set your current marginal bracket and the bracket you realistically expect in retirement; 22 percent now versus 12 percent later favors traditional, the reverse favors Roth. (3) Add the employer match percentage if one exists, since match dollars almost always land pre-tax even when your own contribution is Roth. (4) The projection compounds both scenarios at your expected return, then applies retirement-bracket tax to traditional withdrawals and current-bracket tax to Roth contributions, and reports the after-tax gap. The result is not always decisive; when brackets are close, the tool says so, because in a tie the Roth's flexibility wins.
Roth wins when your tax rate today is lower than your rate at withdrawal, which happens in three common situations: you are early in your career with entry-level income, you expect promotions to push you into higher brackets while you still hold decades of compounding, or you anticipate large taxable income in retirement from pensions, rental properties, or required minimum distributions from other accounts. Traditional wins when you are at peak earnings now and expect leaner taxable income later. Two practical rules sit outside the math: contribute at least enough traditional 401(k) to capture the full employer match before anything else, since a 50 percent match outperforms any tax-bracket arbitrage, and remember Roth contributions can be withdrawn penalty-free in emergencies, making them a dual-purpose emergency reserve for young savers.
Roth wins when your current tax bracket is lower than your expected retirement bracket — typical early in a career. Traditional wins at peak earnings when you expect leaner taxable income later. Always capture the full employer match first; a 50% match beats any tax arbitrage.
The 2026 employee elective deferral limit is $24,500, with an additional $8,000 catch-up for workers 50 and older. Roth IRA limits are lower and phase out at higher incomes; use the calculator to model your split.
Yes, contributions to one do not block the other, though Roth IRA eligibility phases out above roughly $153,000 single / $241,000 married filing jointly in 2026. Combined limits apply per account type, not together.
The accounts end up mathematically equal. In that tie, Roth usually wins on flexibility: contributions can be withdrawn penalty-free, and qualified withdrawals never raise your taxable income in retirement.
It compounds contributions over 10, 20, or 30 years using your marginal tax rate, expected return (default 7% inflation-adjusted), and employer match. The key difference: a 401(k) defers tax on withdrawal while a Roth taxes contributions now but grows tax-free. The tool shows which leaves more after-tax dollars at retirement.
If your current marginal rate is below 22%, the Roth typically wins because you pay tax now at a low rate and withdraw tax-free later. Above the 24% bracket, a traditional 401(k) often yields more after-tax income, especially if you expect a lower rate in retirement.
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