401(k) Paycheck Impact Calculator

Start by entering your current financial situation in the "Income" section. Input your gross annual salary before any taxes or deductions are taken out, and select how often you get paid from the "Pay Frequency" dropdown.

Next, go to the "401(k) Contribution Rates" section. Enter the percentage of your salary you currently contribute to your 401(k) and the new, higher percentage you are considering. This allows the calculator to create a side-by-side comparison.

In the "Tax Rates" section, provide your estimated marginal tax rates. For "Federal Tax Bracket," enter the rate for your highest dollars earned (e.g., 12%, 22%, 24%). Do the same for your "State Tax Rate." These rates are crucial for calculating your tax savings. If you are unsure, a quick search for "2026 federal income tax brackets" can help.

For a more precise estimate, open the "Advanced Settings." Here you can input your "Employer Match" percentage and the "Employer Match Limit" as a percent of your salary. This shows the impact of "free money" from your employer. You can also specify your tax "Filing Status." Capturing your full employer match is one of the most powerful ways to boost your savings, a concept you can explore with our TSP match calculator if you are a federal employee.

Annual Salary and Pay Frequency

Your annual salary is your gross income for the year, before taxes, 401(k) contributions, or other deductions. Pay frequency determines how many paychecks you receive per year (e.g., 26 for biweekly, 12 for monthly) and is used to calculate your per-paycheck breakdown.

Current and Proposed Contribution Rate

The current contribution rate is the percentage of your gross salary you currently save in your 401(k). The proposed contribution rate is the new, higher percentage you want to test. The calculator's main purpose is to show you the real-world difference between these two scenarios. Not sure what rate to aim for? See our guide on how much you should save for retirement each month.

Federal and State Tax Rates

These are your marginal tax rates—the tax you pay on your next dollar of income. Because traditional 401(k) contributions are pre-tax, every dollar you contribute reduces your taxable income by a dollar. The calculator uses these rates to show how much you save on taxes. For example, if you are in the 22% federal bracket and 5% state bracket, contributing an extra $100 could save you $27 in taxes, making the net cost to your paycheck only $73. Learn more about how 401(k) withdrawals are taxed in retirement.

Employer Match and Match Limit

The employer match is the amount your company contributes to your 401(k) on your behalf. It's often expressed as a percentage of your contributions up to a certain limit. For example, a "50% match up to 6%" means your employer adds $0.50 for every dollar you contribute, but only on the first 6% of your salary. The match limit is that maximum percentage of your salary your employer will match contributions on. Failing to contribute enough to get the full match is like turning down a raise.

Filing Status

Your tax filing status (e.g., Single, Married Filing Jointly) helps determine your tax bracket and the standard deduction, which influences your overall tax liability. While this calculator uses a simplified marginal rate, selecting the correct status provides context for your tax inputs.

This calculator provides a simplified model of your paycheck to isolate the financial impact of changing your 401(k) contribution. It does not perform a full tax return calculation but instead focuses on the marginal effect of pre-tax savings.

The methodology involves these steps for both your "Current" and "Proposed" contribution rates:

1. Calculate Gross Pay: Your annual salary is divided by the number of pay periods per year (26 for biweekly, 12 for monthly).
2. Calculate 401(k) Contribution: The gross pay per period is multiplied by your contribution rate (e.g., 6% or 10%).
3. Determine Taxable Income: The 401(k) contribution is subtracted from your gross pay. This is the key step that creates tax savings.
4. Estimate Taxes: The calculator applies your entered federal and state marginal tax rates to the taxable income to estimate taxes owed for that paycheck.
5. Calculate Take-Home Pay: The estimated taxes and your 401(k) contribution are subtracted from your gross pay.
6. Calculate Employer Match: It determines the matched portion of your contribution and calculates the employer's contribution based on the match percentage.

Finally, it compares the two scenarios to calculate the key outputs: the net reduction in take-home pay, the total annual tax savings, and the increase in your annual retirement savings. The calculator does not account for FICA taxes (Social Security and Medicare) or other pre-tax/post-tax deductions like health insurance, as these are typically unaffected by your 401(k) contribution rate.

The calculator computes a per-paycheck breakdown for both the current and proposed scenarios using the following formulas.

Paycheck Breakdown Formulas

pay_periods_per_year = if(pay_frequency is "biweekly", 26, 12)

gross_pay = annual_salary / pay_periods_per_year

contribution_401k = gross_pay * (contribution_rate / 100)

taxable_income = gross_pay - contribution_401k

federal_tax = taxable_income * (federal_tax_bracket / 100)

state_tax = taxable_income * (state_tax_rate / 100)

take_home_pay = gross_pay - contribution_401k - federal_tax - state_tax

employer_match = gross_pay * (min(contribution_rate, employer_match_limit) / 100) * (employer_match_percent / 100)

Comparison and Result Formulas

These formulas compare the "Proposed" scenario to the "Current" one.

paycheck_reduction = current_take_home_pay - proposed_take_home_pay

annual_contribution_increase = (proposed_contribution_401k - current_contribution_401k) * pay_periods_per_year

annual_tax_savings = ((current_federal_tax + current_state_tax) - (proposed_federal_tax + proposed_state_tax)) * pay_periods_per_year

effective_cost_per_dollar = (paycheck_reduction * pay_periods_per_year) / annual_contribution_increase

The effective_cost_per_dollar shows how much your annual take-home pay goes down for every extra dollar you save in your 401(k).

The primary benefit highlighted by this calculator is the tax-deferred nature of traditional 401(k) contributions. When you contribute to a traditional 401(k), the money is taken out of your paycheck before federal and state income taxes are calculated. This directly reduces your Adjusted Gross Income (AGI).

For example, if your gross pay is $3,000 and you contribute 10% ($300) to your 401(k), you are only taxed on the remaining $2,700. If you didn't contribute, you would be taxed on the full $3,000. This immediate tax reduction is why your take-home pay doesn't drop by the full contribution amount.

This differs from a Roth 401(k), where contributions are made with post-tax dollars. With a Roth, your taxable income isn't lowered today, but your qualified withdrawals in retirement are tax-free. The choice between a Roth vs. Traditional IRA or 401(k) depends on whether you expect your tax rate to be higher or lower in retirement.

Your employer's 401(k) match is one of the best investments you can make. It is an instant, guaranteed return on your money. If your employer offers a 100% match on the first 5% you contribute, you are doubling your money on that portion of your savings immediately.

Failing to contribute enough to get the full match is like declining free money. Before you consider any other investment, your first goal should be to contribute at least enough to maximize this benefit. This calculator helps you see just how small the paycheck impact is to capture that full match.

Use the "Proposed Contribution Rate" field to enter your employer's match limit (e.g., 6%). The results will show you the extra employer contribution you'd receive, often for a surprisingly small reduction in take-home pay. This single step can dramatically accelerate your progress toward your retirement savings goals.

It's important to be aware of the annual IRS contribution limits. For 2026, the limits are:

• Employee Contribution Limit: You can contribute up to $23,500 to your 401(k), 403(b), or federal TSP.
• Catch-Up Contribution (Age 50+): If you are age 50 or over, you can contribute an additional $7,500.
• Super Catch-Up (Ages 60-63): Thanks to the SECURE 2.0 Act, individuals aged 60, 61, 62, and 63 can contribute an even higher catch-up amount, projected to be $11,250 in 2026 (the greater of $10,000 indexed for inflation or 150% of the standard catch-up).
• Total Contribution Limit: The combined total of your contributions, your employer's contributions (match and profit sharing), and any after-tax contributions cannot exceed $70,000.

If you are able to max out your 401(k), you might consider saving in other accounts like a Roth IRA or a taxable brokerage account. Use the 401(k) contribution calculator to see if you're on track to hit these limits.

• Paycheck Reduction: This is the most important number. It shows the actual decrease in your take-home pay per pay period. Notice that this amount is less than the increase in your 401(k) deduction, thanks to tax savings.
• Annual Tax Savings: This is the total amount of federal and state income tax you'll save over a full year by increasing your contribution. This money stays in your pocket or, more accurately, is rerouted into your retirement account instead of going to the government.
• Tax Efficiency Score / Effective Cost Per Dollar: The score summarizes how much tax savings offset your contribution. The "effective cost" metric shows this in dollar terms. An effective cost of $0.75 means that for every $1.00 you add to your 401(k), your paycheck only goes down by 75 cents.
• Paycheck Breakdown Chart: This stacked bar chart visually compares your current and proposed paychecks. You can see the 401(k) slice grow while the tax slices shrink, leaving the take-home pay slice only slightly smaller.
• Detailed Comparison Table: This table provides the exact numbers for each component of your paycheck (Gross Pay, 401(k), Taxes, Take-Home, Employer Match) for both scenarios, making the changes crystal clear.

If you want to boost your retirement readiness, use the calculator's insights to take action:

• Capture the Full Match: If the calculator shows you're leaving employer match money on the table, make it your top priority to increase your contribution to the match limit.
• Automate Your Increases: Many 401(k) plans offer an "auto-increase" feature that bumps your contribution rate by 1% each year. This is a painless way to save more over time, as the small change is barely noticeable.
• Commit Your Next Raise: The next time you get a salary increase, use this calculator to see how much of that raise you can direct straight to your 401(k) with zero impact on your current take-home pay.
• Aim for 15%: Most financial experts recommend saving at least 15% of your pre-tax income (including employer match) for retirement. Use the calculator to map out a plan to gradually reach that goal. See how your savings compare to benchmarks in our guide to retirement savings by age.

1. Not getting the full employer match. This is the most common and costly mistake. It is effectively turning down part of your compensation package.
2. Setting it and forgetting it. Failing to increase your contribution rate after you get a raise means you lose a key opportunity to save more without feeling the pinch.
3. Using your gross contribution as the "cost". Many people think contributing $200 more per paycheck will cost them $200. This calculator proves the actual cost to your take-home pay is significantly less.
4. Misunderstanding tax brackets. Using your average tax rate instead of your marginal tax rate will result in an inaccurate calculation of your tax savings.
5. Not considering a Roth 401(k). If you expect to be in a higher tax bracket in retirement, paying taxes now with a Roth 401(k) might be more beneficial than deferring them with a traditional 401(k).