What a Roth IRA projection shows
A Roth IRA is funded with money you have already paid tax on. If the withdrawals later qualify under the tax rules, the growth is not taxed. This calculator projects the balance that follows from the amount you have saved, the amount you add each year, the number of years and an assumed annual return. It then shows how the balance divides between your own contributions and growth, and lets you compare the result with a taxable account under a simple assumption you control.
The default example starts with 30,000, adds 7,500 at the end of each year for 35 years and assumes a 6% effective annual return. That ends at 1,066,343. Of that, 30,000 was already in the account, 262,500 is new contributions and 773,843 is growth. The return is an assumption, not a forecast, and the figures are nominal, with no allowance for inflation or account fees unless you enter a return that is already net of them.
The growth formula
The balance follows one rule each year: last year's balance grows by the return, then the contribution is added. In symbols, B(t) = B(t-1) x (1 + r) + C. With 1,000 to start, 500 added each year for 10 years and a 6% return, the balance is 8,381.25. With a 0% return nothing grows, so the same plan ends at exactly 6,000, which is 1,000 plus ten deposits of 500.
Contributions are added at the end of each year, so each deposit earns nothing in the year it is made. If you invest monthly, your real result is a little higher than shown, because the money works for part of every year. A negative return is allowed, and then the balance can end below what you paid in.
Comparing with a taxable account
The optional comparison puts the same starting money and the same deposits in a hypothetical taxable account. Each year, a share of that year's positive gain is taken as tax, at the rate you enter. There is no tax credit in a losing year, no allowance for carrying losses forward and no tax on selling at the end, so the comparison is a simplified illustration and not a tax model. Real taxable accounts have dividends, realised gains at different rates and a tax when you sell, none of which is modelled.
With the tax rate at 0% both accounts end equal, because there is no tax drag to show. Entering 15% on yearly gains changes the default plan: the taxable account ends at 862,688 against 1,066,343 in the Roth, a gap of 203,655, after 100,621 of tax on gains along the way. The size of that gap depends heavily on the rate you assume, so test a low and a high value. In a falling market the comparison does not favour either account: at a -3% return over 10 years the two end at 87,767 and 87,767.
How much the inputs matter
The return, the years and the yearly amount all matter, but not equally. Cutting the contribution from 7,500 to 5,000 a year lowers the default result from 1,066,343 to 787,757. Keeping the contribution and saving for 20 years instead of 35 gives 372,106. Moving the return to 3% gives 537,881, and 8% gives 1,735,936. The result is one point in a wide range, so treat it as a way to see how the pieces interact, not as a prediction.
Contribution limits and who can use a Roth IRA
For 2026 the IRS limits total contributions to all of your traditional and Roth IRAs to 7,500, or 8,600 if you are 50 or older, or your taxable compensation for the year if that is less. A Roth IRA contribution can also be reduced or barred depending on your filing status and income. The calculator shows a notice if you enter more than the 2026 limit, but it uses the amount you enter and does not decide whether you are eligible. The limits are year-specific and change over time, so check the IRS page for the year you contribute.
If you are still deciding between a Roth and a traditional account, the question is different: you are comparing taxes now with taxes later. Use the Roth vs traditional IRA calculator for that. For other views of the same saving, try the compound interest calculator, the 401k calculator or the retirement planning calculator.
Frequently asked questions
Are Roth IRA withdrawals always tax-free?
Not automatically. The calculator assumes the withdrawals are qualified, which has its own conditions set by the IRS. Withdrawals that do not qualify can be taxed or penalised, and that is not modelled here.
What return should I assume?
Use a cautious figure after fees and run a low and a high case. The calculator holds the return constant, whereas real returns vary every year.
Can I contribute the full amount I enter?
Only if you are eligible and the amount is within the limit that applies to you. The calculator does not check your income, filing status or compensation.
Why do the Roth and taxable results match?
The tax rate on yearly gains is 0% by default, so there is no tax drag to compare. Enter your own assumption to see a difference, keeping in mind that the comparison is simplified.
Is this tax or investment advice?
No. It is an illustration under the assumptions you set and does not promise a return. See the disclaimer.
Sources
Contribution limits: IRS, Retirement topics: IRA contribution limits (page reviewed by the IRS on 23 September 2026, read on 2 November 2026). The 2026 limits are labelled for that year only and are not assumed for any other year.
A small worked check of the comparison: 1,000 to start, 500 a year for 10 years at 6% with 20% tax on yearly gains ends at 8,381.25 in the Roth and 7,828.68 in the taxable account.