Roth 401(k) Calculator

Compare a Roth 401(k) against a Traditional 401(k) to see which plan could leave you with more money after taxes in retirement. This calculator projects the after-tax value of both account types year by year, helping you decide whether to pay taxes now or pay them later. Enter your salary, contribution rate, age, and tax assumptions to find your potential tax savings and break-even point.

This tool is for anyone with a workplace retirement plan trying to choose between pre-tax (Traditional) and post-tax (Roth) contributions. While this calculator focuses on the Roth vs. Traditional decision, you might also find our general 401(k) calculator useful for overall growth projections or the Roth IRA calculator for accounts outside of your employer's plan. Understanding the core differences is key, as explained in our guide to Roth vs. Traditional accounts.

The results provide a clear verdict with a "Roth Advantage Score," showing which option is more favorable based on your inputs. You'll see a side-by-side comparison of your projected after-tax balances at retirement, the total potential tax savings, and a chart illustrating how the after-tax value of each account grows over time.

This calculator is designed for a direct comparison between Roth and Traditional 401(k) options. Start by entering your financial details in the "Income & Contributions" section. Your annual salary and the contribution rate you plan to save determine the total amount you'll invest each year. This calculator automatically caps your contribution at the legal 2026 limit of $23,500.

Next, fill in your "Personal Details." Your current age and planned retirement age set the timeline for your investment growth. A longer timeline typically gives the tax-free growth of a Roth 401(k) more time to compound and pull ahead. The expected annual return is the average growth rate you anticipate for your investments.

The "Tax Brackets" section is crucial for the comparison. Enter your current marginal federal tax bracket and what you expect your federal tax bracket to be in retirement. This is the core of the Roth vs. Traditional trade-off: paying taxes now at your current rate or later at your future rate.

For more detailed planning, open the "Advanced Settings." Here, you can add your employer match percentage, which is a key part of your total retirement savings. You can also include your state tax rate for a more precise tax calculation and specify if you are eligible for catch-up contributions (age 50 and over). If you are a federal employee, our TSP match calculator can provide more specific details on your matching program.

Annual Salary and Contribution Rate

Your annual salary is your gross income before any taxes or deductions. The contribution rate is the percentage of that salary you elect to contribute to your 401(k). Together, these inputs determine your annual contribution amount. For example, a $100,000 salary with a 10% contribution rate means you contribute $10,000 per year. The calculator will automatically apply the 2026 employee contribution limit of $23,500.

Current Age and Retirement Age

Your current age and planned retirement age define your investment time horizon. The more years you have until retirement, the more significant the impact of tax-free compounding becomes. This often makes the Roth 401(k) more advantageous for younger savers who have decades for their investments to grow without the drag of future taxes on that growth.

Expected Annual Return

This is the average annual rate of return you expect your 401(k) investments to generate. It's a long-term estimate, as market performance will vary year to year. A higher expected return will magnify the difference between the two account types, as more growth in a Roth 401(k) means more tax-free money in retirement.

Current and Retirement Tax Brackets

These two inputs are the most important factor in the Roth vs. Traditional decision.

• Current Federal Tax Bracket: Your marginal tax rate today. With a Roth 401(k), you pay this rate on your contributions.
• Retirement Tax Bracket: Your estimated marginal tax rate when you withdraw funds in retirement. With a Traditional 401(k), you pay this rate on all withdrawals.

If you expect your retirement tax rate to be higher than your current rate, the Roth 401(k) is often the better choice. If you expect it to be lower, the Traditional 401(k) may be more advantageous. Our guide on how 401(k) withdrawals are taxed can provide more context.

Employer Match

This is the percentage of your salary your employer contributes to your 401(k), typically up to a certain limit. It's critical to understand that all employer matching funds are contributed on a pre-tax basis, even if you contribute to a Roth 401(k). This means the match portion of your account will grow tax-deferred and be taxed as ordinary income upon withdrawal, just like a Traditional 401(k).

State Tax Rate

Your state income tax rate is added to your federal tax bracket to calculate your total marginal tax rate. Including this provides a more accurate comparison of your after-tax outcomes. If you plan to retire in a different state, consider how that might change your retirement tax burden. You can see a comparison in our article on the best states to retire for taxes.

Catch-Up Eligible (Age 50+)

If you are age 50 or older, you are eligible to make additional "catch-up" contributions above the standard limit. For 2026, the catch-up contribution limit is $7,500. Enabling this option allows the calculator to factor in these higher potential savings.

This calculator runs a parallel projection to compare the after-tax outcomes of investing in a Roth 401(k) versus a Traditional 401(k). It models the growth of your contributions and employer match year by year from your current age to your retirement age.

For the Traditional 401(k) scenario, your full employee contribution and the employer match are invested pre-tax. The entire balance grows tax-deferred. At retirement, the calculator applies your expected retirement tax rate to the final balance to determine its after-tax value.

For the Roth 401(k) scenario, the calculation is split into two parts:

1. Employee Contributions: Your contributions are made after-tax. This portion of your account grows completely tax-free, and qualified withdrawals in retirement are also tax-free.
2. Employer Match: Your employer's contributions are always pre-tax. This portion of your account is segregated, grows tax-deferred, and is taxed at your retirement tax rate upon withdrawal.

The calculator's primary output is the final after-tax balance for each scenario. By comparing these two numbers, it can show you which account type is projected to provide more spending power in retirement based on your tax assumptions. The "break-even year" identifies the age at which the Roth 401(k)'s after-tax value surpasses the Traditional 401(k)'s.

The calculator uses a year-by-year loop to project the balance for each account type. Here are the core formulas used in the annual calculation.

Annual Contribution Formula

The calculator first determines your total employee contribution, ensuring it does not exceed IRS limits.

raw employee contribution = annual salary x (contribution rate / 100)
max allowed contribution = standard limit (23500) + (if eligible, catch-up limit (7500))
annual contribution = min(raw employee contribution, max allowed contribution)

Employer Match Formula

The employer match is calculated based on your salary.

employer match amount = annual salary x (employer match rate / 100)

Traditional 401(k) Projection

For the Traditional 401(k), both employee and employer contributions are pre-tax.

yearly growth = previous year balance x (expected return / 100)
end of year balance = previous year balance + annual contribution + employer match amount + yearly growth

At retirement, the after-tax value is calculated:

traditional after-tax value = final balance x (1 - (retirement federal tax rate + state tax rate) / 100)

Roth 401(k) Projection

The Roth 401(k) has two separate balances: the post-tax employee portion and the pre-tax employer match portion.

// Employee Roth Balance (tax-free growth)
roth employee growth = previous roth employee balance x (expected return / 100)
end of year roth employee balance = previous roth employee balance + annual contribution + roth employee growth

// Employer Match Balance (tax-deferred growth)
employer match growth = previous employer match balance x (expected return / 100)
end of year employer match balance = previous employer match balance + employer match amount + employer match growth

At retirement, only the employer match portion is taxed:

tax on employer match = final employer match balance x ((retirement federal tax rate + state tax rate) / 100)
roth after-tax value = final roth employee balance + (final employer match balance - tax on employer match)

The choice between a Roth and a Traditional 401(k) hinges almost entirely on your current income tax rate versus your expected income tax rate in retirement.

Choose a Roth 401(k) if:

• You expect to be in a higher tax bracket in retirement. This could be due to career growth, higher investment income, or the potential for future tax rates to rise.
• You are early in your career and in a lower tax bracket now than you anticipate being in later.
• You want tax diversification in retirement, giving you a source of tax-free income to manage your taxable income from other sources like a pension or Traditional IRA.
• You want to avoid Required Minimum Distributions (RMDs) on your own contributions. As of 2024, Roth 401(k)s are no longer subject to RMDs for the original owner.

Choose a Traditional 401(k) if:

• You expect to be in a lower tax bracket in retirement. This is common for people at their peak earning years who anticipate living on less income after they stop working.
• You want the largest possible tax deduction right now. Pre-tax contributions reduce your current taxable income, which can be valuable if you're in a high tax bracket today.
• You believe you can invest the tax savings you get today and have that money grow to be worth more than the future tax liability.

Ultimately, the best strategy might be a mix of both. Some employers allow you to split your contributions between Roth and Traditional 401(k) accounts, giving you tax diversification within the same plan.

Knowing the rules that govern Roth 401(k)s is essential for effective retirement planning.

Contribution Limits: For 2026, you can contribute up to $23,500 to your 401(k), whether it's Roth, Traditional, or a combination. If you are age 50 or older, you can contribute an additional $7,500 as a catch-up contribution, for a total of $31,000. Under the SECURE 2.0 Act, those aged 60-63 can make a "super catch-up" contribution of $11,250 (instead of $7,500), for a total of $34,750. Unlike Roth IRAs, there are no income limitations for contributing to a Roth 401(k).

Employer Match: As noted earlier, any matching funds from your employer are always made on a pre-tax basis. They will be held in a separate pre-tax portion of your 401(k) and will be taxable upon withdrawal.

Withdrawal Rules: To withdraw your earnings tax-free from a Roth 401(k), the distribution must be "qualified." This means you must be at least 59½ years old, and it must have been at least five years since your first Roth 401(k) contribution. Your own contributions can always be withdrawn tax- and penalty-free at any time, as you already paid tax on them.

Required Minimum Distributions (RMDs): A major advantage of the Roth 401(k) emerged with the SECURE 2.0 Act. Starting in 2024, Roth 401(k) accounts are no longer subject to RMDs during the original owner's lifetime. This provides more flexibility and allows your tax-free funds to continue growing. If you need to plan for RMDs from other accounts, use our RMD calculator.

Yes, you can absolutely contribute to both a Roth 401(k) and a Roth IRA in the same year, provided you meet the income eligibility requirements for the Roth IRA.

The contribution limits for these accounts are separate. The 401(k) limit ($23,500 in 2026) applies to your workplace plan, while the IRA limit ($7,000 in 2026) applies to your personal IRA. This means an individual under 50 could potentially contribute a total of $30,500 to Roth accounts in a single year.

This strategy is an excellent way to maximize your tax-free retirement savings. However, remember that Roth IRAs have income phase-outs that may prevent high earners from contributing directly. In that case, you might explore a Backdoor Roth IRA.

• Roth Advantage Score: This score, from 1 to 99, summarizes the calculator's findings. A high score (e.g., 80+) suggests the Roth 401(k) is strongly favored based on your inputs, usually because your retirement tax rate is higher than your current one. A low score suggests the Traditional 401(k) may be more beneficial.
• Roth Balance at Retirement: This is the total projected value of your Roth 401(k) at retirement, including both the tax-free employee portion and the pre-tax employer match portion.
• Traditional After-Tax: This shows the projected value of a Traditional 401(k) after subtracting the estimated taxes you'd owe upon withdrawal in retirement. This is the number to compare against the Roth's after-tax value.
• Tax Savings in Retirement: This is the difference between the Roth after-tax value and the Traditional after-tax value. A positive number represents the extra spending power you could have by choosing the Roth option.
• Break-Even Year: This is the age when the after-tax value of the Roth 401(k) is projected to exceed that of the Traditional 401(k). The sooner this happens, the more compelling the Roth option becomes.
• Comparison Chart: This visualizes the growth of the after-tax value for both account types over time. You can see exactly when the lines cross and how the gap widens in favor of one account or the other.

Regardless of which account type you choose, the fundamentals of saving remain the same.

• Contribute Enough for the Full Match: The most important step is to contribute at least enough to get your full employer match. This is free money and often represents a 50% or 100% return on your contribution. Use a 401(k) contribution calculator to see the impact.
• Automate Contribution Increases: If your plan allows, set up automatic annual increases to your contribution rate. A 1% increase each year is often barely noticeable in your paycheck but can dramatically boost your final balance.
• Re-evaluate Your Tax Situation: Your tax situation can change. If you get a large raise, your spouse changes jobs, or tax laws change, re-run this calculator to see if your choice is still the optimal one.
• Consider Tax Diversification: Even if one option looks slightly better, consider splitting your contributions between Roth and Traditional if your plan allows. This gives you flexibility in retirement to manage your taxable income by drawing from different pools of money.
• Explore a Mega Backdoor Roth: If you're a high-income saver and your plan allows for after-tax contributions, you may be able to save far beyond the standard limits using an after-tax 401(k) calculator to explore a "mega backdoor Roth" conversion.

1. Forgetting the Employer Match is Always Pre-Tax: Many people assume their match money also becomes Roth. It does not. It will always be taxable upon withdrawal.
2. Ignoring State Taxes: A 5% or 7% state income tax can significantly impact the calculation, especially if you plan to move from a high-tax state to a no-tax state (or vice-versa) in retirement.
3. Assuming Tax Rates Will Be Lower in Retirement: While this is a common assumption, it's not guaranteed. Future legislation could raise tax rates, or your retirement income from pensions, Social Security, and investments could push you into a higher bracket than expected.
4. Confusing 401(k) and IRA Rules: Roth 401(k)s do not have income limits for contributions, unlike Roth IRAs. Don't assume you earn too much to use your employer's Roth option.
5. Fixating on the Tax Deduction: The immediate gratification of a tax deduction from a Traditional 401(k) is appealing, but it may lead to a much larger tax bill down the road. Consider the total, long-term picture.