Roth 401(k) vs. Traditional 401(k) Calculator
Use this calculator to determine which 401(k) contribution type might be right for you.
How the roth 401(k) vs. traditional 401(k) calculator works
It projects equal contributions to retirement, keeps the Roth balance untaxed, and taxes the traditional balance at your expected retirement rate — then compares the after-tax results.
Worked example: with annual 401(k) contribution of $10,000, years until retirement of 30 and annual return of 7.00%, the roth 401(k) vs traditional 401(k) calculator shows better after-tax outcome of Pre-tax 401(k).
- Roth 401(k) (tax-free)
- $1,010,730
- Pre-tax balance
- $1,329,908
- Pre-tax after tax
- $1,037,329
- Difference
- $26,598
| Tax rate in retirement | Roth | Pre-tax |
|---|---|---|
| 14.00% | $1,010,730 | $1,143,721 |
| 22.00% | $1,010,730 | $1,037,329 |
| 26.00% | $1,010,730 | $984,132 |
| 34.00% | $1,010,730 | $877,740 |
The better choice flips around 26.00% — Roth wins on one side, Pre-tax on the other.
The formula
Both grow as (balance + contribution) × (1 + return). Roth after-tax = balance. Traditional after-tax = balance × (1 − retirement tax rate).
Results are estimates for educational purposes and are not financial advice. Confirm exact figures with your lender, plan administrator or advisor.
Questions about the roth 401(k) vs. traditional 401(k) calculator
Roth or traditional 401(k)?
Roth wins if your retirement tax rate is the same or higher than today’s; traditional can win if your rate will be lower and you invest the upfront tax savings.
What is the core difference?
A Roth 401(k) is funded with after-tax money and withdrawn tax-free; a traditional is funded pre-tax and taxed on withdrawal. The bet is on your future tax rate.
Do both get the employer match?
Yes, but the employer match always goes into a pre-tax (traditional) account, even if your own contributions are Roth. That portion is taxed at withdrawal.
Is the Roth 401(k) vs. Traditional 401(k) Calculator free to use?
Yes. Every calculator on FinCalculators is completely free, with no sign-up, login or paywall. You can run as many scenarios as you like.
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