Roth vs Traditional 401(k) Calculator
Same contribution, same growth — the only difference between Roth and Traditional 401(k) money is when tax is paid. This calculator totals the lifetime tax bill under each choice and shows the net spendable winner. No salary or employer match needed.
Estimates only — not financial advice. This calculator gives approximate figures for planning. It is not financial, tax, or legal advice; check with a qualified professional before making decisions.
How the Roth vs Traditional 401(k) calculator works
Think of your contribution as pre-tax dollars. In the Traditional column, the full amount compounds for the whole period and the retirement tax rate takes its cut of the final balance. In the Roth column, today’s tax rate is paid on each contribution up front and the shrunken remainder compounds tax-free. Same dollars, same growth — so the two tax rates alone decide which path costs less in lifetime tax.
This is the pure tax-cost view: no salary, no employer match, no balance projections — just the tax bill. If your retirement rate will be lower than today’s, Traditional usually costs less; if it will be higher, Roth usually wins. Equal rates are a dead tie.
FV = annual × ((1+g)n−1)/g · only the two tax rates move the winner
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Roth vs Traditional 401(k) calculator FAQ
Is a Roth vs Traditional 401(k) the same question as a 401(k) vs Roth 401(k) calculator?
Yes — same question, different phrasing. This page answers it by lifetime tax cost; if you also want the employer match and balance projection modeled, see our 401(k) vs Roth 401(k) calculator.
Which 401(k) costs less in taxes overall?
Whichever faces the lower tax rate. Compare your marginal rate today with your expected marginal rate in retirement: the lower rate wins, because the math is otherwise identical. Run your numbers above.
What if my tax rates are equal now and in retirement?
Then it is a mathematical tie — paying x% on the way in versus x% on the way out leaves the same spendable money. Tie-breakers: required minimum distributions, estate plans, and tax diversification.
Does the employer match change this comparison?
No — the match is always pre-tax and taxed at withdrawal no matter which bucket your own dollars go in, so it cancels out. It is modeled explicitly in our 401(k) vs Roth 401(k) calculator.
Can I split my contributions between Roth and Traditional?
Yes, most plans allow it. Splitting hedges against guessing your future tax rate wrong — the result lands between the two all-in scenarios this calculator shows.