Roth IRA Calculator

The IRA Calculator on this site already runs Traditional, Roth, and Taxable side by side for anyone still deciding between them. This page assumes you have already leaned Roth and zooms in on what actually makes it different: the tax bill lands upfront, not at withdrawal, and that single fact changes which inputs matter and which real-world rules you need to know about.

The Formula, and Why the Order of Operations Matters

This calculator's Roth line is: FV = P x (1 minus your current tax rate) x (1 + r)^n. Notice what is missing compared to a Traditional IRA formula: there is no future tax rate anywhere in it. The tax haircut happens once, immediately, on the principal, before growth ever starts. Everything that compounds after that point is yours, untaxed, at withdrawal.

A Two-Scenario Example

Hold everything else constant at the calculator's defaults, a $100,000 balance, a 6% return, ages 40 to 65, and only change the current tax rate:

• At a 25% current tax rate: roughly $321,900 after 25 years.
• At a 15% current tax rate: roughly $364,800 after 25 years.

That is a meaningful swing driven entirely by one input. Since the future tax rate field on this page never touches the Roth calculation, your current tax rate is the only tax assumption doing any work.

A Note for High Earners: Income Limits and the Backdoor Roth

Real Roth IRAs are not open to everyone at every income level. Direct contributions phase out above certain modified AGI thresholds set by the IRS each year. If your income is above that line, the common workaround is a "backdoor Roth": contribute to a non-deductible Traditional IRA, then convert it to Roth shortly after. The tax math on the converted amount ends up similar to what this calculator models, but the conversion step itself, along with the pro-rata rule if you hold other pre-tax IRA money, is not something this tool simulates. Treat the numbers here as the growth projection once money is inside a Roth, not as a substitute for that eligibility check.

Frequently Asked Questions

Q: I changed Expected Tax Rate at Retirement and my Roth number didn't move. Is that right?

Yes. The Roth formula never uses that field. Once you have paid tax on your contribution at today's rate, qualified Roth withdrawals are tax-free, so no future tax rate assumption enters the math. That field still affects the Traditional IRA and Taxable Savings lines on the same screen, which is why it is there at all.

Q: Real Roth IRAs have income limits. Does this calculator enforce them?

No. This tool assumes you are eligible to contribute. If your income is above the current-year threshold, a backdoor Roth can achieve a similar tax outcome for new money, though the math above does not model the conversion step itself.

Q: Can I withdraw my Roth contributions before retirement without penalty?

Generally yes for your original contributions, not the earnings, once the account has been open five tax years, since you already paid income tax on that money going in. Earnings withdrawn early are typically subject to both tax and a penalty unless an exception applies. This calculator projects growth only; it does not model early-withdrawal scenarios.

Q: Why does lowering my current tax rate increase my projected Roth balance?

Because a lower current tax rate means less of your principal is lost to the upfront tax bill, leaving more money to compound for the rest of the horizon. See the two-scenario example above.

For the Traditional-vs-Roth side-by-side, or to model a plain taxable brokerage account too, use the IRA Calculator.