Roth vs Traditional 401(k) Calculator: Which Saves You More?

The short answer: compare your tax rate now with your tax rate on withdrawals

A traditional 401(k) saves you tax now and taxes the withdrawals later. A Roth 401(k) taxes the money now and lets qualified withdrawals come out tax-free. If both grow the same way, the choice comes down to one comparison: if your tax rate on the contribution today is higher than the rate you'll pay on the withdrawals, traditional wins; if it's lower, Roth wins. (If you contribute the maximum, Roth gets a small extra edge; see below.)

Example: a single 35-year-old in Texas earning $75,000 who puts 10% in saves $1,650 of tax a year with traditional, a rate of 22%. With $24,000 a year of Social Security in retirement, the withdrawals would be taxed at about 12.1% on average. Traditional gives $26,468 a year after tax in retirement against $23,480 for Roth. The calculator works this out for your own numbers.

How to compare them fairly

Many Roth-vs-traditional comparisons put the same dollar amount into each account and ignore the tax a traditional contribution saves. That flatters Roth, because a $7,500 Roth contribution costs you more take-home pay than a $7,500 traditional one. The fair test holds your take-home cost equal:

Roth contribution = traditional contribution − tax saved now = the Roth you could afford instead

$7,500 traditional saves $1,650 of tax, so it costs $5,850 of take-home. Spending the same $5,850 on a Roth means a $5,850 Roth contribution instead of $7,500 traditional.

With equal growth, traditional gives you the balance times (1 − your retirement tax rate) and Roth gives you the balance times (1 − your tax rate today), so the rates decide it. Fidelity's point is related: the tax you save now only helps if you invest it rather than spend it (Fidelity). The one exception is when you contribute the maximum. Then you can't add more to the Roth, and the comparison changes (see below).

Your tax rate now: federal and state

The tax a traditional contribution saves is your federal and state rate on the last dollars you earn. We work it out from the paycheck engine, so it's exact for your state, including states that tax 401(k) contributions. Same $75,000 single filer saving 10%, in five states:

Pennsylvania is the odd one out: it taxes 401(k) contributions, so traditional saves only federal tax there, but it doesn't tax qualifying withdrawals after retirement (Pennsylvania Department of Revenue). Illinois doesn't tax 401(k) withdrawals at all (Illinois Department of Revenue), so the state tax you save now is a pure gain with traditional.

Your tax rate in retirement: withdrawals fill the brackets from the bottom

Your retirement rate isn't your top bracket. Withdrawals fill the standard deduction first ($16,100 single or $32,200 joint in 2026, plus $2,050 single or $1,650 per spouse at 65 and over), then the 10% and 12% brackets (Rev. Proc. 2025-32). So the average tax on a moderate withdrawal is often well below the rate you save today. That's why traditional often wins for people who retire on modest incomes.

It works the other way for people with large pensions or big traditional balances. With $100,000 of pension and other taxable income in retirement, a $90,000 earner in Texas would pay about 24% on the withdrawals against 22% saved now; Roth comes out ahead by $722 a year. Early in a career it often flips: at $40,000, a 24-year-old saves only 12% now, and a mix does best at the default assumptions.

The 2025 tax law also added a $6,000 deduction for people 65 and over, but only for 2025 through 2028, so we leave it out for future retirees (IRS).

How Social Security changes the answer (the "tax torpedo")

Part of your Social Security becomes taxable once your "provisional income" (other income plus half your benefits) passes $25,000 single or $32,000 joint: up to 50% of benefits, rising to up to 85% above $34,000 single or $44,000 joint. Those thresholds have never been raised for inflation (IRS Publication 915; IRS Topic 423). Traditional withdrawals count toward provisional income; qualified Roth withdrawals don't. In the middle range, each extra dollar withdrawn also makes 50 or 85 cents of benefits taxable, so the effective rate jumps:

An effective rate above 20% while your income is still in the 10% or 12% bracket is one of the strongest arguments for putting some savings in Roth, and the calculators we reviewed ignore it. Ours includes it, with the thresholds shrinking in real terms each year because they aren't indexed.

State taxes: where you work vs where you retire

• Moving to a no-tax state in retirement (Florida, Texas, Nevada and others) makes traditional more attractive: you save state tax now and pay none later. A $180,000 earner in California who maxes out gets $81,263 a year after tax from traditional if they retire to a no-tax state, against $78,581 if they stay.
• States that don't tax 401(k) withdrawals: Illinois, Iowa (from age 55), Mississippi and Pennsylvania (after retirement), on top of the states with no income tax (Illinois; Iowa; AARP on Mississippi, where early withdrawals don't qualify; Pennsylvania). New York excludes up to $20,000 a year from age 59½, and Colorado and others exclude part of it. Choose the state you'll retire in and the calculator applies its 2026 brackets to your withdrawals, with 0 for those four states and New York's exclusion; for other states' partial breaks, enter your own rate.

If you max out: Roth shelters more, but doesn't always win

The $24,500 limit is the same for Roth and traditional (IRS), but a Roth dollar is worth more because the tax is already paid. If you're contributing the maximum, Roth lets you shelter more money from tax, because the traditional saver has to put the tax saved now in an ordinary taxable account. That narrows the gap but doesn't always reverse it. Choose "The maximum" in the calculator to compare it that way. At $180,000 in California, staying put, traditional still comes out ahead by $4,740 a year, because the tax saved now (33.3%) is so much higher than the expected rate on withdrawals (22.2%).

Mixing Roth and traditional

You don't have to choose one. Plans let you split each paycheck, and the shared limit applies to the total. A common approach is to use traditional for the dollars taxed at your highest rate today, and Roth for the rest, so withdrawals in retirement come from both buckets. The calculator shows the half-and-half result next to each choice. Having both also lets you control your taxable income in retirement year by year, which helps with the Social Security thresholds above.

Only a minority use Roth today: Vanguard reports that 98% of its plans offer a Roth option but just 18% of participants use it (Vanguard How America Saves 2026).

The Roth catch-up rule for earners over $150,000

From 2026, if your FICA wages from the employer were over $150,000 last year, any catch-up contributions at 50 and older must go in as Roth. The final rules are mandatory from 2027, and for 2026 plans must follow a good-faith reading of the law; if your plan has no Roth option, you generally can't make catch-up contributions at all (IRS). Your regular $24,500 can still be traditional. The calculator applies this automatically: for a 55-year-old earning $200,000 who maxes out, the $8,000 catch-up is Roth either way, so only the $24,500 is compared. See how it splits each paycheck in the 401(k) paycheck calculator.

Employer match, RMDs and access to your money

• Employer match: usually pre-tax whichever you choose, so it's taxed when you withdraw it. Since the SECURE 2.0 Act, plans may let you take the match as Roth if it's fully vested, but then it counts as taxable income in the year it's made (IRS Notice 2024-2).
• Required minimum distributions: since 2024, Roth money in a 401(k) has no required withdrawals during your lifetime; traditional money does, from age 73, or 75 if you were born in 1960 or later under the SECURE 2.0 Act (IRS). That makes Roth useful for money you may never need, or want to leave to heirs.
• Qualified Roth withdrawals need you to be 59½ (or disabled, or the account passes at death) and to have had a Roth in the plan for five tax years (IRS). Taking money out early costs a 10% additional tax on the taxable part unless an exception applies, such as leaving your job in or after the year you turn 55 (IRS).
• No income limit: unlike a Roth IRA, a Roth 401(k) is open to everyone whatever they earn.

Common mistakes in Roth vs traditional comparisons

• Same contribution, ignoring the tax saved. It makes Roth look better than it is unless you're maxing out.
• Using your top bracket for retirement. Withdrawals start in the lowest brackets; the average rate is usually lower.
• Leaving out state tax at either end, or Pennsylvania's different treatment.
• Ignoring Social Security taxation, which can push the real rate on withdrawals well above the bracket.
• Saying Roth 401(k)s have RMDs. Not since 2024.

2026 401(k) limits

See the 2027 limits as they're announced.

Common questions

Is it better to do Roth or traditional 401(k)?

Traditional if your tax rate today is higher than your expected rate on withdrawals; Roth if it's lower. Many people split contributions because future tax rates are uncertain.

Should I do Roth 401(k) if I'm in the 22% bracket?

It depends on your retirement income. In the example above, a single Texas filer at $75,000 (22% bracket) does better with traditional because withdrawals would be taxed at about 12.1% on average. With a large pension or big traditional balances, Roth can win.

Can I contribute to both a Roth and traditional 401(k)?

Yes, if your plan offers both. The $24,500 limit applies to the total.

Is there an income limit for a Roth 401(k)?

No. Income limits apply only to Roth IRAs.

Does Roth 401(k) have required minimum distributions?

No, not since 2024. Traditional 401(k)s require withdrawals from age 73, or 75 if you were born in 1960 or later.

Do Roth withdrawals affect Social Security taxes?

Qualified Roth withdrawals don't count toward provisional income, so they don't make more of your benefits taxable. Traditional withdrawals do.

Is my employer match Roth?

Usually not: it goes in pre-tax. Some plans now offer a Roth match, which is taxable when it's paid in.

What if I'll retire in a state with no income tax?

That favors traditional: you save state tax now and pay none on withdrawals. Enter 0 as the state rate in retirement.

Sources

1. Retirement plans FAQs on designated Roth accounts — Internal Revenue Service. Accessed October 15, 2026.
2. 401(k) limit increases to $24,500 for 2026, IRA limit increases to $7,500 (IR-2025-111) — Internal Revenue Service. Accessed October 15, 2026.
3. Treasury, IRS issue final regulations on new Roth catch-up rule (IR-2025-91) — Internal Revenue Service. Accessed October 15, 2026.
4. Retirement plan and IRA required minimum distributions FAQs — Internal Revenue Service. Accessed October 15, 2026.
5. Notice 2024-2 (SECURE 2.0 guidance, including Roth employer contributions) — Internal Revenue Service. Accessed October 15, 2026.
6. Publication 915, Social Security and Equivalent Railroad Retirement Benefits — Internal Revenue Service. Accessed October 15, 2026.
7. Topic no. 423, Social Security and equivalent railroad retirement benefits — Internal Revenue Service. Accessed October 15, 2026.
8. Revenue Procedure 2025-32 (2026 inflation adjustments) — Internal Revenue Service. Accessed October 15, 2026.
9. One, Big, Beautiful Bill Act: tax deductions for working Americans and seniors — Internal Revenue Service. Accessed October 15, 2026.
10. Retirement topics: exceptions to tax on early distributions — Internal Revenue Service. Accessed October 15, 2026.
11. Pension and retirement income — Illinois Department of Revenue. Accessed October 15, 2026.
12. Retirement income tax guidance — Iowa Department of Revenue. Accessed October 15, 2026.
13. PA personal income tax guide: gross compensation — Pennsylvania Department of Revenue. Accessed October 15, 2026.
14. Mississippi state tax guide — AARP. Accessed October 15, 2026. Secondary source.
15. How America Saves 2026 — Vanguard. Accessed October 15, 2026.
16. Spender or saver? Roth vs. traditional — Fidelity. Accessed October 15, 2026.

Results are estimates in today's dollars under 2026 tax law. We're not financial advisers; check your plan's rules and consider professional advice for your own situation. Research checked October 15, 2026.