Traditional vs Roth Calculator

What Is the Traditional vs Roth Calculator?

This tool compares the after-tax value at retirement of the same pre-tax contribution amount, invested either in a Traditional account (grows tax-deferred, taxed at withdrawal) or a Roth account (contributes only the after-tax portion up front, grows and withdraws tax-free). The standard rule of thumb: Traditional tends to win if your tax rate will be lower in retirement than it is now; Roth tends to win if it'll be higher. The result depends entirely on the tax rates you enter -- nobody can predict future tax rates with certainty, so treat this as a sensitivity check under your own assumptions, not a guaranteed outcome.

How to Use This Tool

Enter your contribution amount, your current tax rate, your estimated tax rate in retirement, an expected annual return, and years until withdrawal. Both scenarios' after-tax value appear side by side.

The Model Behind the Comparison

The calculator uses the standard same-pre-tax-dollar comparison. It grows a single contribution over your stated number of years at a steady annual return. On the Traditional side, the full pre-tax amount grows and is then reduced by your assumed retirement tax rate. On the Roth side, you first pay tax at your current rate, so only the after-tax remainder is invested, and that grows with no further tax.

A useful consequence: the growth factor appears on both sides, so it cancels out of the comparison. The winner depends only on whether your retirement rate is lower or higher than your current rate. If the two are equal, the results tie; if your retirement rate is lower, Traditional comes out ahead; if higher, Roth does. The return and years inputs change the dollar amounts but not which side wins.

Worked Example With Hypothetical Numbers

Using 6,000 dollars, a 22 percent current rate, a 12 percent retirement rate, 7 percent return and 25 years: the growth factor is about 5.43. Traditional: 6,000 x 5.43 = about 32,600, times 0.88 leaves about 28,700. Roth: 6,000 x 0.78 = 4,680, times 5.43 is about 25,400. Traditional wins by roughly 3,300 dollars in this scenario. Switch the retirement rate to 22 percent and the two land at the same figure; set it to 30 percent and Roth pulls ahead.

What the Calculator Does Not Capture

• It models one contribution, not a yearly series, though the winner logic is the same for each contribution.
• It assumes you invest the tax savings if you choose Traditional. In this model the Roth side simply contributes less, which is the standard framing, but real people who take the Traditional deduction and spend the refund get a different outcome.
• Marginal rates are treated as single flat percentages. In reality retirement income is spread across brackets, and withdrawals can interact with Social Security taxation, Medicare premium surcharges and required minimum distributions.
• Future tax law is unknown. Rates and brackets may differ in decades. A mix of both account types is one way some people hedge that uncertainty.
• Eligibility rules, income limits for direct Roth IRA contributions, and employer match treatment are outside the tool. Confirm current rules at IRS.gov.

Choosing Your Rate Inputs Wisely

The most common error is entering an average or effective rate rather than a marginal one. Your current marginal rate is the tax on your next dollar of income; look at your latest return or a paycheck-based estimate. For retirement, think about expected income sources rather than simply assuming a lower number. Someone with a large pension, rental income and Social Security may not fall into a lower bracket than during their working years. Run the tool with a range, such as 10, 15 and 22 percent, to see how sensitive the outcome is.

This is a simplified educational model, not personalized tax advice; a tax professional or fiduciary planner can assess your full situation.

Frequently Asked Questions