Roth vs Traditional 401(k) Calculator
The only real difference between a Roth and traditional 401(k) is when you pay tax: now (Roth) or in retirement (traditional). This calculator compares the after-tax outcome at your tax rates.
How to use this calculator
- Enter annual contribution.
- Enter years until retirement.
- Enter annual investment return.
- Enter your marginal tax rate today.
- Enter expected marginal tax rate in retirement.
- Your results appear instantly below and update as you change the numbers.
How this calculator works
A traditional contribution goes in pre-tax and is taxed when withdrawn; a Roth contribution is taxed today and withdrawn tax-free. This calculator grows the same dollar amount either way, then applies each account's tax treatment: the traditional balance is reduced by your retirement tax rate, while the Roth balance is reduced by your current rate on the contribution itself. Whichever after-tax value is higher wins. With equal tax rates the result is identical — the decision comes down to whether you expect to be in a higher or lower bracket later.
Frequently asked questions
Which one is better?
If you expect a lower tax rate in retirement than today, traditional wins. If you expect a higher rate — common early in your career — Roth wins. If rates are equal, the math is identical, and diversification across both types is a reasonable hedge.
Can I have both a Roth and traditional 401(k)?
Yes — most plans let you split contributions between the two, and the $24,500 (2026) limit is shared across both. Splitting gives you tax flexibility in retirement.
Does the employer match count?
Employer matching contributions always go in pre-tax, regardless of which type you choose. The match is identical either way, so it does not change the comparison — but always contribute enough to get the full match first.
Disclaimer: Results are estimates for general information only and do not constitute financial, tax, or legal advice. Figures reflect 2026 rules and may change. Always confirm current limits and consult a qualified professional before making decisions. Official figures: IRS.gov · 2026 limits per IRS tax inflation adjustments.