Roth vs Traditional Contribution Calculator

Read the calculator result

This calculator compares two uses of the same annual pretax earnings budget. The traditional scenario contributes the whole budget before the assumed income tax. The Roth scenario pays that tax first and contributes the remainder. Both balances then earn the same entered annual return for the same number of years. At the comparison date, the traditional balance is reduced by an entered withdrawal tax rate; the Roth balance is treated as available tax free under a qualified-distribution assumption.

The question is narrower than choosing an entire retirement strategy. It asks how two tax rates change the ending value of otherwise identical contributions. It doesn’t decide whether an account is available to you, whether a traditional IRA contribution is deductible, whether a distribution qualifies, or whether you should convert an existing balance. The amounts and rates shown initially are illustrations, not current contribution limits or tax brackets.

The IRS explanation of designated Roth contributions distinguishes contributions made after income tax from pretax salary deferrals. It also explains that tax-free treatment of Roth earnings depends on qualified-distribution rules. Check the rules for your particular plan or account before interpreting the Roth outcome as money you could withdraw without tax.

Roth vs traditional: enter a comparable budget and tax assumption

Start with the annual earnings amount you can direct toward retirement before the modeled income tax. If that amount is $6,000 and the current tax rate is 24%, the traditional contribution is $6,000. The Roth contribution is $4,560, because $1,440 of the same earnings budget is allocated to current tax. This is an equal-budget comparison even though the account contributions differ.

The current tax rate should represent the income-tax difference associated with the modeled contribution. It isn’t automatically your average tax rate on all household income. The retirement tax rate represents the assumed tax on the traditional withdrawals being compared. The tool applies one flat percentage to the ending balance for clarity. A real withdrawal plan can cross brackets, vary by year, and interact with other income; none of those effects is estimated here.

Enter an effective annual investment return, after any costs you intend to include, and whole contribution years. Contributions occur at each year’s end, so the last contribution receives no growth before the final comparison. The tool doesn’t model monthly payroll timing or a balance already accumulated. Keep the same investment assumptions on both sides if your purpose is to isolate tax treatment.

How the calculator works

Let B be the annual pretax budget, t the current tax rate as a decimal, u the retirement tax rate, r the annual return, and n the number of years. Annual traditional contributions equal B, while annual Roth contributions equal B × (1 − t). Each year, the previous balance grows by 1 + r before the new contribution is added.

Traditional balance before withdrawal tax = B × [((1 + r)ⁿ − 1) ÷ r]. Traditional balance after tax = that balance × (1 − u). Roth balance = B × (1 − t) × [((1 + r)ⁿ − 1) ÷ r].

When the return is zero, the growth factor becomes n. The calculation uses that limit rather than dividing by zero. The displayed traditional advantage is its after-tax balance minus the Roth balance. A negative advantage means the Roth scenario ends higher under the entered assumptions; it isn’t a prediction about future tax legislation or market returns.

There’s no additional taxable investment account for traditional tax savings. The traditional side already invests the entire pretax budget, while the Roth side uses part of that same budget for tax. Adding another investment of $1,440 each year to the traditional side would count the same tax difference twice. An equal-contribution comparison with an independently funded tax bill would require a different household budget.

Roth vs traditional calculator example: $6,000 a year for 30 years

Use a $6,000 annual pretax budget, a 24% current tax rate, a 22% retirement tax rate, a 6% annual return, and 30 years. Total pretax earnings committed are $180,000. Each annual Roth contribution is $4,560, while the traditional account receives $6,000. No starting account balance, employer contribution, conversion, or taxable side account is included.

The traditional scenario is ahead by $9,486.98 because the assumed retirement tax rate is lower than the current rate. Its much larger balance before withdrawal tax isn’t the amount available to spend in this model. Comparing $474,349.12 directly with the Roth result would omit the traditional withdrawal tax and exaggerate the difference.

Amounts are rounded for display after the calculation. Annual contributions remain constant in nominal dollars; the model doesn’t automatically raise them with inflation or salary. To evaluate purchasing power, use the same inflation assumption for both ending amounts rather than treating the larger future dollar total as an unchanged amount of today’s spending.

Find the tax-rate crossover

Change only the retirement tax rate to 24%. Both after-tax balances become $360,505.33. With identical return and contribution timing, the common growth factor cancels, so the break-even retirement rate equals the current 24% rate. This equality is a consequence of the defined model, not a rule that every real Roth decision can be reduced to one tax bracket.

At a 30% retirement tax rate, the traditional after-tax balance falls to $332,044.38. The Roth result stays $360,505.33 and is ahead by $28,460.95. The investments haven’t changed; only the tax retained from traditional withdrawals has changed. Record several plausible withdrawal-rate scenarios instead of selecting a single favorable number and treating it as certain.

At a zero investment return, the traditional account accumulates $180,000 before tax and $140,400 after the original 22% tax assumption. Roth contributions total $136,800. The traditional difference is then $3,600. Growth magnifies the dollar effect of the tax-rate difference, but it doesn’t change the equal-rate crossover within this construction.

Read the balance chart on a consistent basis

The annual return is a constant scenario, not a sequence of market outcomes. Two accounts can hold different investments in practice, but comparing different returns here would mix tax treatment with investment selection. Establish the tax comparison with matched returns first. Only then consider separate investment-cost or allocation questions using a framework that keeps those additional differences visible.

The original chart and its year-by-year table show the accumulation path under your current inputs. Use the after-tax comparison when assessing spendable amounts. Any traditional balance before tax is a separate reference, not an additional pool of money. Year zero starts at zero, and every later row reflects growth followed by the end-of-year contribution.

Changing the retirement tax rate alters the traditional after-tax path without changing its underlying account balance. Changing the current rate alters the Roth contribution and path. Changing the investment return affects both accounts. These different responses help identify whether a result is driven by contribution size, growth, or the final tax assumption.

Use the result in a broader contribution decision

First, confirm the retirement arrangement actually offers the contribution types you’re comparing. Second, establish a sustainable pretax budget. Third, obtain reasonable current and future tax assumptions that apply to the specific dollars involved. Fourth, compare several horizons and rates. Keep a record of those assumptions so a later change in income or retirement timing can be evaluated against the same framework.

Employer matching contributions can materially change the household outcome, but this model excludes them. Use the 401(k) match calculator to examine an entered matching formula and contribution timing separately. Don’t add a match to only one side unless your plan actually treats the alternatives differently and you have modeled that difference explicitly.

For an overall accumulation target, the retirement savings calculator includes a starting balance and monthly savings. The investment fee calculator can isolate how different charges affect growth. Their results answer different questions and shouldn’t be added together as if each represents a separate investment balance.

Roth vs traditional calculator questions

Does this estimate my tax refund or tax bill?

No. It applies the percentages you enter to a defined contribution and withdrawal scenario. It doesn’t calculate taxable income, deductions, credits, filing status, payroll taxes, or state-specific treatment. A tax return can produce a different incremental effect from a simple rate assumption.

Why are equal $6,000 contributions not used?

Funding a $6,000 Roth contribution after a 24% modeled income tax requires more pretax earnings than funding a $6,000 traditional contribution. Equal account deposits would answer a different question unless the additional Roth tax cost were also included. This calculator deliberately keeps the earnings budget equal.

Does a higher result identify the right account for me?

It identifies the higher ending amount in this scenario. Access rules, required withdrawals, beneficiaries, liquidity, contribution limits, employer terms, and the value of holding different tax treatments can also matter. The model doesn’t quantify those considerations or establish that a withdrawal is qualified.

Can I use this for a Roth conversion?

No. A conversion starts with an existing balance and may involve a tax payment from inside or outside the account. This calculator instead models repeated new contributions from an equal annual earnings budget. Entering a conversion balance as an annual contribution would distort both timing and cost.