⚖️ Roth vs Traditional IRA Calculator

Roth vs Traditional IRA: Which Account Builds More After-Tax Wealth?

Choosing between a Roth IRA and a Traditional IRA is one of the most consequential decisions you can make as a retirement saver — yet many investors pick one almost at random, or simply follow what a parent did. The truth is that neither account is universally superior. The right choice depends almost entirely on a single question: will your marginal income tax rate be higher now or in retirement? Getting that answer right can be worth tens of thousands of dollars over a long investing career.

The Core Structural Difference

Both Roth and Traditional IRAs let your investments grow without annual capital-gains or dividend taxes — that tax-deferred compounding is the shared advantage they both offer over a taxable brokerage account. The accounts diverge in when taxes are collected.

Traditional IRA: Contributions are typically tax-deductible in the year you make them (subject to income limits if you also have a workplace plan). Your money grows tax-deferred. Every dollar you withdraw in retirement is taxed as ordinary income at whatever rates apply then.

Roth IRA: Contributions are made with after-tax dollars — no deduction today. Your money grows completely tax-free. Qualified withdrawals in retirement are 100% tax-free, with no requirement to ever touch the money if you do not need it.

The Mathematical Logic: A Fair Comparison

To compare the two accounts fairly you must start from the same gross income. Suppose your gross contribution budget is $7,000. If you choose a Roth, you contribute $7,000 in pre-tax earnings — but after paying a 22% marginal tax rate, only $5,460 actually enters the account. If you choose a Traditional IRA, you deduct the full $7,000 and invest all of it, saving $1,540 in taxes today (which you may or may not invest elsewhere — most people do not).

Using the future value of an annuity formula — FV = PMT × ((1 + r)ⁿ − 1) / r — both accounts earn the same gross return. The question is what happens at the finish line:

• Roth balance: fully yours, zero tax due. The $5,460 annual contribution compounding at 7% for 30 years becomes roughly $516,000 in after-tax dollars.
• Traditional balance: the full $7,000 annual contribution compounding at 7% for 30 years grows to about $661,000 gross — but at a 22% retirement tax rate you keep about $516,000 after taxes.

When the tax rates are equal, the after-tax outcome is mathematically identical. This is not a coincidence — it is the fundamental algebra of tax-deferred vs. tax-exempt accounts. Every percentage-point difference between your current and future marginal rate tips the scales in one direction.

When the Roth IRA Wins

If you expect your retirement tax rate to be higher than your current rate, the Roth wins. This is common for:

• Early-career earners currently in the 10% or 12% bracket who expect to earn more over time and retire with significant income from multiple sources.
• People with large Traditional IRA or 401(k) balances — required minimum distributions (RMDs) starting at age 73 can push taxable income into higher brackets even if you do not need the money.
• Tax-rate optimists who believe federal marginal rates will rise in the future (e.g., after the 2017 tax cuts sunset in 2025).
• Those seeking flexibility — Roth contributions (not earnings) can be withdrawn at any time without penalty, providing an accessible emergency layer.

When the Traditional IRA Wins

If you expect your retirement tax rate to be lower than your current rate, the Traditional IRA wins by shifting income from a high-rate period to a low-rate one:

• Peak-earning years — a surgeon, attorney, or executive in the 32%–37% bracket who plans to spend much less in retirement may easily drop to the 22% or even 12% bracket.
• Those with modest retirement spending goals whose Social Security plus portfolio withdrawals stay in lower brackets.
• People who will invest the upfront tax savings — if you genuinely redirect that $1,540 annual tax refund into a taxable account, Traditional can win even at equal rates (though this requires discipline).

The Break-Even Tax Rate Rule

The break-even formula is simple: if your current marginal tax rate equals your effective retirement tax rate on withdrawals, the accounts tie. Every point higher in retirement favors Roth; every point lower favors Traditional. Note that "retirement tax rate" means your marginal rate on IRA withdrawals — not your overall effective rate — because every additional dollar withdrawn is taxed at the marginal rate.

Five Other Factors Beyond the Math

1. Required Minimum Distributions: Traditional IRAs (and most 401(k)s) force withdrawals starting at 73. Roth IRAs have no RMDs during the owner's lifetime, making them powerful estate-planning tools and hedges against living a very long life.

2. Income Limits: Roth IRA contributions phase out for single filers above $146,000 and joint filers above $230,000 (2024). Traditional IRA deductibility phases out at lower thresholds if you have a workplace plan. High earners who can use neither deductible Traditional nor direct Roth may use the "backdoor Roth" strategy.

3. State Taxes: Some states exempt Traditional IRA withdrawals; others do not. Your state's retirement income rules can meaningfully shift the break-even point. A taxpayer moving from California (high state income tax) to Florida (no state income tax) in retirement tilts heavily toward Traditional.

4. Tax Diversification: Many advisors suggest holding both types of accounts so you have flexibility to draw from the lower-tax-cost source each year in retirement — a strategy called "tax-efficient withdrawal sequencing." This is especially valuable when you cannot predict future tax law.

5. Contribution Limits: The annual IRA contribution limit is $7,000 for 2024 ($8,000 if you are 50 or older). Because a Roth contribution represents fewer pre-tax dollars than the same Traditional contribution from the same gross budget, some argue a Roth "stuffs" more real economic value into the same statutory limit — though the calculator above models this correctly through the gross-contribution framework.

How to Use This Calculator

Enter your planned annual contribution in gross (pre-tax) terms — this is the total amount of gross income you are allocating to retirement savings. Set your current marginal federal income tax rate (the rate on your last dollar of income, not your effective rate). Set the retirement marginal tax rate you expect when you will withdraw funds. Adjust the annual return and years to retirement, then click Calculate.

The tool computes the future value of annual contributions using a standard annuity formula, applies the relevant tax treatment at each stage, and presents both the gross accumulated balance and the after-tax spendable amount. The difference tells you exactly how much each choice is worth in today's decision.

The Bottom Line

There is no universal winner between Roth and Traditional IRA — the right answer is deeply personal and changes over the course of a career. Young earners in low brackets should nearly always favor Roth; high-income earners near peak earnings should lean Traditional; everyone in between benefits from modeling both scenarios. Use this calculator with your actual marginal tax rates, revisit it as your income changes, and consider holding both account types for maximum flexibility. The decision you make consistently and early matters far more than the one you optimize perfectly but implement late.