Roth vs. Traditional IRA Calculator

A Roth vs. Traditional IRA calculator runs the same dollar through two different tax timelines and tells you which finish line has more money on it. The core question it answers: is your tax rate higher today or higher in retirement? If today is higher, the Traditional IRA usually wins because you’re deducting at a high bracket and pulling out at a lower one. If retirement is higher, Roth usually wins because you paid tax at a lower bracket on the way in. Every Roth vs. Traditional IRA calculator boils down to that bracket comparison plus a few mechanical adjustments.

Here’s the math the tool is running. Say you’re a 38-year-old in the 24% federal bracket plus 6.85% New York State plus 3.876% NYC, for a combined marginal rate of roughly 34.7%. You put $7,500 into a Traditional IRA and deduct it. The actual cost to you is $7,500 minus $2,429 in tax savings, so $4,571 out of pocket. To make an apples-to-apples comparison, the Roth vs. Traditional IRA calculator assumes you also invest that $2,429 of tax savings in a regular brokerage account. Otherwise the comparison is rigged against Traditional. People skip this step constantly and end up favoring Roth on accident.

Now fast-forward 27 years to age 65. Both accounts grew at, say, 7% annually. The Traditional IRA grew to about $43,200. The brokerage side car holding the tax savings grew too, but it got dragged down by annual taxes on dividends and capital gains turnover—call that an effective drag of 0.5% per year, so it landed at roughly $13,400 after embedded gains tax. Withdraw the Traditional at a 22% federal plus 6.85% state retirement bracket (you’re in lower income years), and the $43,200 nets about $30,700. Add the brokerage side car, and the total after-tax pot is about $44,100. That’s what a Traditional pathway actually produces when you account for the reinvested tax savings.

Same $7,500 into a Roth IRA. No deduction, so it costs the full $7,500 out of pocket. After 27 years at 7%, it’s about $43,200. Tax-free on withdrawal. Total after-tax pot: $43,200. Traditional wins by about $900 in this scenario, mostly because the side car kept compounding alongside the IRA. The margin is thin enough that small assumption changes flip it.

Flip the assumptions. Same client, but they retire to Florida (no state tax) and end up in a 12% federal bracket because Social Security plus modest withdrawals keep them under the 22% threshold. Traditional withdrawal nets $38,000. Roth still nets $43,200. Roth wins by $5,200. A Roth vs. Traditional IRA calculator isn’t guessing—it’s doing the bracket arithmetic you’d do yourself if you had three hours and a clean spreadsheet. The retirement bracket assumption is the single most important input, and most people underestimate it.

The calculator’s output is sensitive to four inputs above all others: your current marginal bracket, your projected retirement bracket, the number of years until withdrawal, and whether you’ll also invest the Traditional tax savings. Get those four right and the answer stabilizes quickly. Most people accept the calculator’s default retirement bracket of 22% without thinking, which biases the result toward Roth. If you’re a NYC professional planning to retire in NYC, your retirement bracket might still be 24%+ once you stack federal, state, and city. That changes the answer materially.

One thing a Roth vs. Traditional IRA calculator can’t do is predict future tax law. Brackets sunset at the end of 2025 unless Congress acts, and depending on which extension passes the 22% bracket could revert to 25% and the 24% to 28%. If you assume tomorrow’s rates are higher across the board, the Roth bias gets stronger. We typically run two scenarios for clients: current law continues, and brackets revert. If Roth wins both, the answer’s clear. If they split, we look at flexibility (Roth has no RMDs at 73 under SECURE 2.0; Traditional does) and decide from there.

There’s a subtle compounding factor most calculators don’t surface. The IRS Uniform Lifetime Table starts RMDs at age 73 with a divisor of about 26.5, meaning roughly 3.77% of your Traditional balance must come out that year as taxable income. By age 85 the divisor drops to about 16, meaning 6.25% must come out. The Traditional account’s “tax-deferred” status is really “tax-postponed,” and the postponement ends at 73 whether you wanted income or not. The Roth has no RMD during the original owner’s lifetime, which means a Roth lets you control your AGI for IRMAA Medicare surcharges, capital gains brackets, and Social Security taxation. The Roth vs. Traditional IRA calculator that scores only end-of-life dollars misses this strategic value.

A useful sanity check: if the calculator’s output is within 5% either direction, treat it as a tie and decide on flexibility instead. Run your own numbers using our Roth IRA calculator and Traditional IRA calculator for single-account views, or use this Roth vs. Traditional IRA calculator side-by-side to see the bracket arbitrage spelled out.

One more variable a Roth vs. Traditional IRA calculator should weight: investment selection inside each account. If you’re putting REITs, high-yield bonds, or actively-managed mutual funds with high turnover into one of the two accounts, the Roth shields you from the annual tax drag those produce. A Traditional already shields you the same way during accumulation. So if you’re going to hold tax-inefficient assets in either account, the choice of account type matters less than the fact that you held them in a tax shelter. Tax-efficient index funds, by contrast, behave well in a taxable brokerage account, which means the “side car” assumption for Traditional is more realistic when you’re indexing. Plug your actual investment style into the calculator if it lets you, not just a blanket 7% growth number.

A Roth vs Traditional IRA calculator is doing bracket comparison, and the bracket gap between a 26-year-old paralegal and her future 65-year-old self is almost always positive—meaning her future bracket will be higher than her current one. She’s making $72,000 today and sitting in the 22% federal bracket. By 45 she’ll likely be in 24%. By the time she retires with a $2M portfolio plus Social Security, withdrawals could push her into 24% or 32% depending on how brackets evolve. Roth wins. The calculator isn’t magic; it’s just running that arithmetic.

The 2026 marginal brackets are 10%, 12%, 22%, 24%, 32%, 35%, and 37%. The huge cliff between 12% and 22% is where the Roth case is strongest. If you’re in the 12% bracket today as a single filer (under about $48,000 of taxable income), almost any plausible retirement scenario lands you at 22%+ later. The Roth vs Traditional IRA calculator picks Roth basically every time in that range. A graduate student earning $40,000 should be doing Roth contributions exclusively unless they need the deduction for some other reason like qualifying for a Saver’s Credit, which has its own income test.

Now flip to a high earner. A 49-year-old NYC banker making $620,000 of W-2 income, married filing jointly. She’s in the 35% federal bracket plus 6.85% New York State plus 3.876% NYC, combined marginal rate north of 45%. Her husband’s a freelance illustrator with modest income. Two issues immediately: she’s phased out of direct Roth contributions (MFJ phaseout is $242,000–$252,000 for 2026, and she’s way past it), and she’s phased out of deducting her Traditional IRA contribution because she’s covered by a 401(k) at work (MFJ active-participant phaseout is $126,000–$146,000). So her direct options are: nondeductible Traditional, or backdoor Roth.

Where Traditional logic still applies: her husband. He’s not covered by a workplace plan. The Spousal IRA rule lets him contribute $7,500 (or $8,600 if 50+) using her earned income, and because she’s the covered spouse, the deduction for HIS Traditional IRA contribution phases out between $242,000 and $252,000 MFJ. They’re past that too. So his Traditional contribution is also nondeductible. The Roth vs Traditional IRA calculator output for this couple shows that direct deductible Traditional is off the table—the comparison is really nondeductible Traditional vs. backdoor Roth, and backdoor Roth wins almost every time because tax-free growth beats taxable growth on the same starting basis.

For peak earners in 32%+ brackets who still have access to deductible options through a workplace plan, Traditional 401(k) contributions almost always beat Roth 401(k). The same Roth vs. Traditional IRA calculator logic applies at the 401(k) level, just with bigger numbers ($24,500 elective deferral plus $8,000 catch-up for 2026). Defer at 37% federal, withdraw later at 22% or 24%, capture the 13–15 point bracket spread. That’s real money compounded over decades. We model this for high-income clients constantly and the answer is consistent: Traditional 401(k) for the deferral, Roth IRA via backdoor for the supplemental piece, and conversions to clean up the Traditional balance later in life.

There’s one wrinkle that makes the “Roth for young, Traditional for old” rule less clean: the Roth IRA has no required minimum distributions during the original owner’s lifetime. Traditional IRAs require RMDs starting at age 73 under SECURE 2.0, computed using the IRS Uniform Lifetime Table. If you don’t need the money, the RMD forces taxable income you didn’t want. Roth doesn’t. So even when the bracket math favors Traditional, some clients put a slice into Roth specifically for flexibility—to control their AGI in retirement, manage IRMAA Medicare surcharges, and leave a tax-free inheritance to heirs (Roth inherited IRAs still have the 10-year drawdown rule under SECURE Act, but with zero tax on withdrawals). A Roth vs Traditional IRA calculator that only optimizes for end-of-life dollars will miss this nuance entirely.

The surprise here: middle earners in the 22% bracket are where the answer gets genuinely hard. The bracket spread between 22% (now) and 22% (retirement) is zero, so the calculator’s output gets dominated by secondary effects—side car investment drag, RMD pressure, IRMAA thresholds, and assumed future law. We typically default mid-bracket clients to Roth for the flexibility unless they need the current-year deduction to claim another credit or stay under an income threshold. A $7,500 Traditional deduction can keep you under a phaseout for the Child Tax Credit, the American Opportunity Credit, the Premium Tax Credit on a marketplace health plan, or the Net Investment Income Tax threshold. That secondary tax benefit can be worth more than the bracket spread itself.

One last factor a good Roth vs Traditional IRA calculator should surface: the marginal “effective” bracket isn’t always your statutory bracket. Social Security taxation creates a phantom bracket between roughly $25,000 and $44,000 of provisional income for single filers where each additional dollar of IRA withdrawal causes 50¢ or 85¢ of Social Security to become taxable. The real marginal rate in that zone can be 22.2%, 27.75%, or 40.7% depending on where you are. A Roth withdrawal doesn’t count toward provisional income; a Traditional does. For modest-income retirees, this single factor can swing the answer back toward Roth even when statutory brackets look favorable for Traditional. For a full strategy review, see our tax strategy consulting page.

The Roth vs Traditional IRA calculator also misses an emotional factor that’s real in practice: regret risk. A young saver who picks Traditional and watches tax rates climb for 30 years will second-guess the choice every year. A young saver who picks Roth and watches rates fall has at least preserved optionality. For 20-somethings the dollars are small and the decades are long, so we typically just say: do Roth, don’t overthink it. Once you’re 35+ with real income, run the actual numbers. The calculator becomes meaningful when contribution dollars get large enough to matter.

Some can, most can’t do it well. The backdoor Roth is a workaround for high earners who are phased out of direct Roth contributions: contribute $7,500 to a Traditional IRA on a nondeductible basis (everyone can do this, no income limit), then convert that Traditional to a Roth shortly after. The end state is $7,500 in a Roth IRA that you wouldn’t otherwise be allowed to fund. A Roth vs. Traditional IRA calculator that doesn’t address the backdoor leaves a giant gap for anyone above the MFJ $252,000 Roth phaseout. We use the backdoor for almost every high-income client.

The mechanics are simple. The trap is the pro-rata rule under IRC §408(d)(2). If you have ANY existing pre-tax balance in a Traditional IRA, SEP-IRA, or SIMPLE IRA on December 31 of the conversion year, the IRS treats your Roth conversion as a pro-rata mix of pre-tax and after-tax dollars. Example: you do a $7,500 nondeductible contribution intending to convert it tax-free, but you also have a $93,000 rollover Traditional IRA from an old 401(k). Your basis is $7,500 out of a total $100,000, so 7% of the conversion is tax-free and 93% gets taxed at your ordinary rate. The $7,500 conversion produces $6,510 of taxable income. At a combined NYC marginal rate of 45%+, that’s about $2,930 of unexpected tax. People run a Roth vs. Traditional IRA calculator, see “backdoor Roth is free,” and skip this check. Don’t.

A Roth vs. Traditional IRA calculator that handles the backdoor properly will ask you for your aggregate pre-tax Traditional IRA balance across ALL accounts before computing the conversion tax cost. If it doesn’t ask, it’s assuming you have zero pre-tax balance, which is true for maybe 30% of the high-income clients we work with. The other 70% have an old 401(k) rollover sitting somewhere they forgot about. That balance has to be aggregated even if it lives at a different brokerage. The IRS looks at the December 31 balance across all your IRA-type accounts as one combined number for pro-rata purposes.

The cleanest fix for the pro-rata problem is to roll the existing pre-tax balance INTO an employer 401(k) plan if your current plan accepts incoming rollovers. 401(k) balances don’t count toward the pro-rata calculation; only IRA-type accounts do. Once the pre-tax IRA balance is at zero on December 31, the backdoor Roth conversion is fully tax-free. We do this for clients every January: empty the IRA into the current 401(k), then run the backdoor through the year. Some plans don’t accept incoming rollovers—check your plan document before assuming. Fidelity, Schwab, and Vanguard-administered plans almost always accept them; smaller TPA-run plans sometimes don’t.

For 2026, the same $7,500 contribution limit applies to the backdoor as to a direct Roth. If you and your spouse both have earned income (or qualify under the Spousal IRA rule), that’s $14,000 of backdoor Roth a year, $16,000 if both are 50+. Over 20 years at 7%, that’s about $580,000 of tax-free retirement money you wouldn’t otherwise have access to. Worth doing. The Roth vs. Traditional IRA calculator should let you toggle “backdoor Roth” on and show the projected balance against a nondeductible Traditional left in place. The tax-free growth versus taxed earnings spread is significant over decades.

The mega backdoor is a different animal and lives inside your workplace 401(k), not your IRA. If your plan allows after-tax (non-Roth, non-pre-tax) contributions AND in-service conversions to the Roth subaccount or in-service rollovers to a Roth IRA, you can stuff far more than the $7,500 IRA limit into a Roth wrapper. The 2026 total annual addition limit for a 401(k) is $72,000. Subtract your $24,500 elective deferral and your employer match (say $15,000), and you’ve got room for $31,500 of after-tax contributions that can be Roth-converted. That’s the mega backdoor. A Roth vs. Traditional IRA calculator won’t cover this—you need a 401(k)-level model—but if you’re in this income range, the question to ask your HR or plan administrator is whether your plan supports after-tax contributions and in-service conversions. Not every plan does. Tech companies and big-law firms usually do; smaller plans often don’t.

The reporting trail matters. Every nondeductible Traditional contribution gets reported on Form 8606 in the year you make it. The conversion gets reported on Form 8606 again in the year you convert. The brokerage will send you a 1099-R for the conversion showing the gross distribution; you reconcile the basis on Form 8606 so the taxable portion is correctly computed. If you skip the 8606 for the contribution year, the IRS has no record of your basis and will tax the conversion in full when you eventually do it. That’s a $7,500 mistake at high brackets. The Roth vs. Traditional IRA calculator output should remind you about Form 8606; few do.

One unusual outcome the calculator should flag: the backdoor Roth doesn’t make sense for everyone above the phaseout. If you’re a 62-year-old planning to retire at 65 and convert your existing Traditional balances to Roth in your 60s anyway, an additional $7,500 nondeductible Traditional contribution adds complexity (Form 8606 basis tracking) for marginal benefit. We’d rather see that $7,500 go to a taxable brokerage account where it gets capital gains treatment and step-up at death. The backdoor Roth is a great move for 35-year-old high earners with 30 years of compounding ahead. For 62-year-olds it’s a draw.

For specifics on coordinating backdoor and mega backdoor across both spouses’ income, the firm’s high net worth client page covers how we approach this. Or submit a New Client Inquiry to have us model it for your numbers using a real Roth vs. Traditional IRA calculator built for your situation.

One last reality check the Roth vs. Traditional IRA calculator should surface for backdoor users: the “step transaction doctrine” concern that floated around for years is essentially dead. The Joint Committee on Taxation blue book accompanying the 2017 TCJA explicitly acknowledged the backdoor Roth as a legitimate strategy. As long as you correctly report the nondeductible contribution on Form 8606 and report the conversion separately on the next Form 8606, the IRS treats it as two distinct steps. You don’t need to wait months between contribution and conversion. Same-day backdoor conversions are fine. The pro-rata rule and the basis tracking are where mistakes actually happen, not the timing.

A Roth vs. Traditional IRA calculator built for conversions is different from one built for contributions. The contribution calculator asks “which type should I fund this year?” The conversion calculator asks “should I move existing Traditional dollars into a Roth by paying tax now at my current bracket?” Same underlying bracket arithmetic, different inputs, and a much bigger dollar exposure because conversions can involve six-figure balances. You can do a $200,000 conversion in a single year; you can’t make a $200,000 contribution.

The setup we look for: a client retired at 64, hasn’t started Social Security yet (delaying to 70 for the 8% per year deferral credit), has $1.2M in a rollover Traditional IRA, and is living off cash reserves. Their taxable income is essentially zero. They’re sitting in the 10% federal bracket with room to fill the 12% and 22% brackets before hitting 24%. The 2026 top of the 22% bracket is approximately $103,350 single, $206,700 MFJ. A Roth vs. Traditional IRA calculator—in conversion mode—tells them they can convert about $103,000 a year at an effective federal rate of about 17%, far below the 24% or 32% bracket they were paying on those dollars when they earned them. That’s pure bracket arbitrage. Do that for six years (64 to 70 before RMDs and Social Security pile in) and you’ve moved $618,000 from Traditional to Roth at a blended rate that’s 7–15 points cheaper than the original deduction. The lifetime tax savings on that block is comfortably six figures.

What the Roth vs. Traditional IRA calculator needs to know to give you a real answer: your current taxable income before conversion, your filing status, your state of residence (state tax matters—California taxes conversions at 13.3% at the top, Florida and Texas zero), your projected income at age 73 when RMDs start, your expected Social Security benefit, and your charitable giving plans (QCDs after 70 1/2 can satisfy RMDs without taxable income). Plug those in and the calculator should produce a per-year conversion target that maxes out a chosen bracket without spilling into the next one.

Don’t convert blindly all in one year. A $1.2M conversion in a single year for a married couple lands them in the 32% federal bracket and triggers the 3.8% net investment income tax on other income, IRMAA Medicare surcharges that’ll bite two years later, and possibly state-level pain. The Roth vs. Traditional IRA calculator output should show year-by-year incremental conversions sized to specific bracket ceilings: fill 12%, then 22%, then evaluate whether 24% still makes sense. We typically stop at the top of the bracket the client expects to be in during their RMD years. Converting into a bracket higher than your future RMD bracket is paying tax early at a worse rate. That’s the opposite of the goal.

IRMAA is a sleeper cost a basic Roth vs. Traditional IRA calculator usually ignores. Medicare Part B and Part D surcharges are computed off your MAGI from two years prior. The 2026 surcharges add roughly $70/month to over $400/month per person on top of the standard premium, depending on which tier your MAGI lands in. A big conversion in 2026 spikes your MAGI, which raises your IRMAA premiums in 2028 by potentially $5,000+ per couple for the year. The conversion math has to net out that future Medicare cost or you’ll be surprised by it. We model IRMAA inside every conversion projection because clients otherwise miss it.

The five-year rule applies to conversions. Every Roth conversion starts its own five-year clock for withdrawing the converted principal penalty-free if you’re under 59 1/2. Earnings on conversions follow the standard Roth earnings rule (59 1/2 AND five years from your first Roth contribution of any kind). For most retirees doing conversions in their 60s this doesn’t matter because they’re already past 59 1/2 and the principal is freely withdrawable. For a 52-year-old converting big numbers, the five-year clock is real and the Roth vs. Traditional IRA calculator should flag it. Pulling converted principal at 54 (two years after conversion at 52) triggers a 10% penalty on the principal.

State-level math is a second sleeper issue. New York City residents pay state plus city tax on conversions at their NYC marginal rate (combined 6.85% + 3.876% at the top end, less below). Converting $100,000 in NYC costs an extra $10,700 of state and city tax vs. converting that same $100,000 in Florida. If you’re planning to move to Florida in two years, defer the conversion. If you’re a permanent New Yorker, factor the city tax in upfront. A Roth vs. Traditional IRA calculator that doesn’t ask your state is giving you a federal-only answer. Stack the state on top and the math changes meaningfully.

Surprising line for this section: the worst time to convert is the year you retire and have a full year of W-2 income plus severance plus accrued bonus. The best time is the year after, when your income drops to near zero and you can fill three brackets cheaply. We see clients convert in their final working year because they “had the money” from a bonus—and they pay tax at 37% on conversions that could have been done at 17% twelve months later. A Roth vs. Traditional IRA calculator run on a year-by-year timeline catches this immediately. People hate waiting a year; the calculator forces the conversation.

The conversion decision is a multi-year strategy, not a single-year choice. We model the full 5-to-10 year window from retirement to RMD age, layered with Social Security claiming and any other income (rentals, pension, deferred comp). Then we work backward from the RMD year and convert just enough each year to land at a lower lifetime tax than doing nothing. For help running this on your numbers, see our tax strategy consulting service or run quick projections using our full calculator library.