Roth IRA Calculator
See what yearly Roth IRA contributions grow to tax free and compare the after-tax result with a traditional IRA and a taxable brokerage account.
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About this toolWhat is the Roth IRA Calculator?
The Roth IRA Calculator shows what a yearly contribution grows to by retirement and, more usefully, whether a Roth IRA actually beats the alternatives for you. It runs the same money through three accounts at once: a Roth IRA, a deductible traditional IRA and an ordinary taxable brokerage account, then reports what each is worth after every tax has been paid.
The answer mostly turns on two numbers you choose: your marginal tax rate today and the rate you expect to pay on withdrawals in retirement. The calculator also handles the less obvious parts, such as what you do with the tax saving from a traditional contribution and how dividends and capital gains slowly tax a brokerage account.
The 2026 IRA limit of $7,500 (plus $1,100 from age 50) is built in and editable, and the 2026 income ranges where Roth eligibility phases out are listed for reference with links to the IRS.
- Roth, traditional and taxable accounts compared after all taxes
- Optional reinvestment of the traditional IRA tax deduction
- Annual dividend tax drag and capital gains on sale for the taxable account
- 2026 IRA limit check with the age 50 catch-up, editable by year
- 2026 Roth income phase-out ranges with IRS links
How to use the Roth IRA Calculator
- Enter your current age and the age you expect to start withdrawals.
- Enter the amount you will contribute each year and any amount already saved.
- Set an expected return and the dividend yield of your investments.
- Enter your marginal tax rate now, the rate you expect in retirement and your capital gains rate.
- Choose whether the traditional IRA's tax deduction is invested, then read the three after-tax totals and the chart.
Worked examples
Slightly higher tax in retirement
Input
$7,500 a year for 35 years at 7%, 22% now, 24% later, 15% capital gains, 2% dividends, deduction invested
Output
Roth $1,109,351; traditional $1,052,060; taxable $949,788 after tax
You contribute $262,500 in each case. The Roth wins by about $57,000 because the retirement rate is higher than today's and the invested deduction is itself taxed in a brokerage account.
High earner now, modest income later
Input
Same, but 32% now and 12% in retirement
Output
Traditional $1,280,161 against Roth $1,109,351
Deducting at 32% and paying 12% later is a 20-point tax arbitrage. This is the profile where a traditional IRA or a pre-tax 401(k) usually comes out ahead.
Spending the refund
Input
22% now and 22% later, deduction not invested
Output
Roth $1,109,351; traditional $865,294
With equal rates the accounts would tie if the refund were invested. Spending it leaves the traditional IRA 22% smaller, which is why the Roth often wins in practice for people who do not reinvest.
Background and insight
A Roth contribution is made with money that has already been taxed, then grows and comes out tax free once you are 59½ and the account has been open five years. A traditional contribution is deducted now and taxed as ordinary income when withdrawn. If both earn the same return and your tax rate is the same at both ends, the two give identical after-tax results, because multiplication is commutative: C × (1 − t) × growth equals C × growth × (1 − t).
That equivalence only holds if the traditional IRA's tax refund is invested too. A $7,500 traditional contribution at a 22% rate saves $1,650 of tax this year, so to compare fairly the calculator can put that $1,650 into a taxable account each year. Turn that switch off and you see the common real-world case where the refund is spent, which tilts the result toward Roth.
For 2026 the IRS phases out direct Roth contributions between $153,000 and $168,000 of modified AGI for single filers and heads of household, between $242,000 and $252,000 for married couples filing jointly, and between $0 and $10,000 for married filing separately. The calculator lists these but does not test your eligibility, because modified AGI has its own definition and the reduced limit inside the range needs the IRS worksheet.
Common use cases
Choosing Roth or traditional this year
Compare your current bracket with a realistic retirement bracket to see which way the numbers lean.
Valuing the tax-free wrapper
See how much a Roth IRA saves over simply investing the same money in a brokerage account.
Planning a backdoor or spousal contribution
Model the growth of the contribution before you deal with the paperwork for the route you use.
Teaching tax diversification
Show why holding both pre-tax and Roth money hedges against not knowing future tax rates.
Tips and limitations
- Your retirement tax rate is a guess. Running a range (for example 12%, 22% and 24%) is more honest than picking one number.
- The IRA limit is shared across all your traditional and Roth IRAs, and you cannot contribute more than your taxable compensation for the year.
- Traditional IRA deductions phase out if you or your spouse are covered by a workplace plan and your income is above the IRS ranges. A non-deductible traditional IRA is not modelled here.
- Early withdrawals of Roth earnings before 59½ and five years are usually taxed and penalised. Contributions themselves can come out at any time.
- This calculator compares federal-style marginal rates. State tax, credits and the effect of the deduction on other parts of your return are left out.
Frequently asked questions
How much can I put in a Roth IRA in 2026?
The 2026 IRA limit is $7,500, or $8,600 if you are 50 or older, shared across all your Roth and traditional IRAs. You also cannot contribute more than your earned income for the year, and the amount you can put directly into a Roth shrinks as your modified AGI enters the phase-out range.
What are the Roth IRA income limits for 2026?
The phase-out ranges are $153,000 to $168,000 for single and head of household filers, $242,000 to $252,000 for married filing jointly, and $0 to $10,000 for married filing separately if you lived with your spouse. Below the range you can contribute the full amount; above it, nothing directly.
Is a Roth IRA better than a traditional IRA?
It is better when your tax rate in retirement will be higher than your rate today, and worse when it will be lower. With equal rates they tie mathematically, provided you invest the traditional IRA's tax refund. Many people hold both because future tax rates are unknown.
How much will my Roth IRA be worth in 30 years?
At $7,500 a year invested at the start of each year and a 7% return, 30 years of contributions grow to about $758,000. The calculator gives the exact figure for your inputs and shows it next to a traditional IRA and a taxable account.
Why does the calculator invest the traditional IRA tax savings?
Because a $7,500 traditional contribution only costs you $7,500 minus the tax it saves. Investing that saving makes all three options cost the same out of pocket, which is the only fair way to compare them. Switch it off to model spending the refund.
Does a Roth IRA beat a regular brokerage account?
Almost always over long periods, because the brokerage account pays tax on dividends every year and on gains when sold. In the default scenario the Roth ends about $160,000 ahead after 35 years on the same contributions.
Is there an in-depth guide to the Roth IRA Calculator?
Yes. “401(k), Roth IRA and Annuities: The Maths Behind Retirement Accounts” covers the background, how it works, common pitfalls and worked examples. Read the full guide.
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