Roth vs Traditional IRA/401(k) Calculator

The choice between Roth and Traditional accounts comes down to one question: will your tax rate be higher now or in retirement? To answer it concretely, this tool compares the after-tax value you would actually keep from each path, using the marginal tax rate you enter for today and the one you expect in retirement. It does not look up tax brackets for you, so check which bracket your taxable income falls in before you enter the rates.

The comparison holds your take-home cost equal. On the Traditional side, the same after-tax budget buys a larger pre-tax contribution: the amount you enter plus the tax the deduction saves, which is amount × current rate ÷ (1 − current rate). All of it grows until retirement, and the retirement tax rate is applied to the withdrawal. The Roth side is simpler: you contribute already-taxed dollars, let them compound, and withdraw the full amount tax-free. Whichever path leaves more money in your pocket after taxes is the one the calculator flags as the winner.

One assumption worth questioning is that your current bracket will follow you into retirement, since income often shifts up or down once paychecks stop. State income taxes also deserve attention, as they can take a meaningful bite out of your net withdrawals depending on where you live. Weigh whether you expect to earn more or less later before you commit to either account type.