Roth vs Traditional 401(k) and IRA Calculator
Compare the after-tax value of Roth and traditional retirement contributions from your tax rate now, your expected rate in retirement and years of growth.
Last reviewed
Contributing $10,000 pre-tax dollars at a 24% tax rate today, growing for 25 years at 7%, leaves $42,334 after-tax in a Traditional account versus $41,248 in a Roth. The result: Traditional wins by $1,085 at a 22% retirement tax rate.
Traditional (after-tax)
$42,334
Roth (after-tax)
$41,248
Your Numbers
This compares the same pre-tax dollars either way. It doesn't model Roth IRA income limits (check irs.gov) or RMD timing differences.
After-Tax Value at Withdrawal
25 years, 7% growth
The Tax-Rate Bet Behind Roth vs Traditional
Every dollar of pre-tax income you set aside for retirement eventually gets taxed once: either now (Roth) or later (Traditional). Because it's the same pre-tax dollar either way, the comparison isn't really about which account "grows more." It's a bet on whether your tax rate today is higher or lower than your tax rate when you withdraw.
The Comparison
Worked example. $10,000 of pre-tax income, taxed at 24% today if you go Roth, growing at 7% for 25 years (a 5.4274× multiple), taxed at 22% on withdrawal if you go Traditional: the Traditional account ends with about $42,334 after tax, and the Roth account ends with about $41,248. Traditional wins by roughly $1,086 because the retirement rate (22%) is lower than the current rate (24%). If the retirement rate were higher than the current rate instead, Roth would win. The math is symmetric.
What this doesn't cover. This tool doesn't model Roth IRA income eligibility limits (they exist and are adjusted periodically — confirm your eligibility at irs.gov before contributing), doesn't account for state taxes, doesn't model RMD timing differences between account types, and assumes you'd invest the same pre-tax dollar amount either way (in practice, some savers max out a Roth account with after-tax dollars, which is effectively saving more). Talk to a fee-only financial planner or tax professional about your specific bracket and goals.
Frequently Asked Questions
?What's the real difference between Roth and Traditional?
Traditional contributions go in pre-tax (reducing your taxable income now) and withdrawals in retirement are taxed as ordinary income. Roth contributions go in after-tax (no deduction now) and qualified withdrawals in retirement are completely tax-free, including all the growth. The comparison ultimately comes down to your tax rate now versus your expected tax rate when you withdraw.
?Why does this calculator show the same amount for both when the rates are equal?
That's the core insight: if your tax rate is identical now and in retirement, Traditional and Roth produce mathematically identical after-tax outcomes for the same amount of pre-tax income. The Traditional account holds more pre-tax dollars but owes tax on withdrawal; the Roth account holds fewer dollars (since tax came out up front) but owes nothing later. At equal rates, those two effects exactly cancel.
?So which one should I actually pick?
If you expect your tax rate to be lower in retirement than it is today (common for many savers, since income often drops after leaving full-time work), Traditional tends to come out ahead. If you expect your rate to be the same or higher in retirement (for example, you're early in your career, expect significant future raises, or worry tax rates in general could rise), Roth tends to come out ahead. Many people split contributions between both to hedge the uncertainty.
?Are there income limits on contributing to a Roth IRA?
Yes. The IRS phases out Roth IRA eligibility at higher modified adjusted gross income levels, and the exact thresholds are adjusted most years. Because the 2026 phase-out ranges weren't consistent across the sources we checked, we're not stating a specific number here. Confirm your eligibility directly at irs.gov before contributing. Roth 401(k)s, by contrast, have no income limit.
?Does this account for required minimum distributions (RMDs)?
No, this calculator only compares the after-tax value of the pot at withdrawal; it doesn't model RMD timing. One relevant fact for a fuller picture: traditional 401(k)s and IRAs require RMDs starting at your required beginning age, while Roth IRAs never require RMDs for the original owner, and since 2024 Roth 401(k)s and 403(b)s no longer require RMDs during the original owner's lifetime either.
About this calculator. Results are estimates for education and planning, based on the inputs you enter and the published formula described above. Everything runs in your browser; nothing you type is sent to us or stored. It is not financial, tax, legal or medical advice. Read the disclaimer and our methodology.
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