401(k) Paycheck Impact Calculator
See how raising your 401(k) contribution changes your take-home pay, what each pre-tax dollar really costs after taxes, and how much match you forfeit.
401(k) Paycheck Impact Calculator
Your paycheck
Enter your salary and contribution, then add your employer match to see the full picture. Contributions are modeled as traditional (pre-tax).
Enter your annual salary.
2026 estimate using IRS brackets, the $24,500 elective limit (or $32,500 with the age-50 catch-up), and a simplified flat state rate. Traditional deferrals reduce federal and state taxable wages but not FICA. Graduated-state rates use the top marginal rate and will overstate tax at lower incomes. Roth contributions are post-tax and would drop your check by the full amount. Not filing-grade: it excludes local taxes, itemized deductions, and credits.
How 401(k) contributions change your take-home pay
Traditional 401(k) money comes out of your check before federal and state income tax gets figured. So a deferral pulls double duty: it moves money into your retirement account, and it lowers the wages the government taxes on that check. That is why your take-home never falls by the full amount you contribute. For someone in the 22 percent federal bracket, a $100 deferral plus a little state tax might trim the paycheck by only about $78. The rest was tax you would have paid anyway.
The number worth watching is net cost per dollar. It answers what you actually want to know: for every $1 I send to my 401(k), how much does my paycheck really shrink? The calculator above shows it straight, next to your take-home before and after, so you can size a contribution against your budget instead of guessing.
Why your paycheck drops less than you contribute
The gap between what you contribute and how much your paycheck actually drops is your income-tax saving. Deferrals lower your federal taxable wages, and in nearly every state that taxes wages, your state taxable wages too, so those savings stack. FICA is the exception. Social Security (6.2 percent up to the 2026 wage base of $184,500) and Medicare (1.45 percent on all wages) still come off your full gross pay. That is why your saving tracks your income-tax rate rather than your full marginal rate: the FICA slice gets charged on the deferred dollars either way.
Do not leave the employer match on the table
Employer matches usually read like "50 percent up to 6 percent": the company kicks in 50 cents per dollar you contribute, on the first 6 percent of your pay. Contribute below that cap and you forfeit part of the match, and that is money gone for good. The tool splits match captured from match forfeited so the trade-off is easy to see. A match is an instant, guaranteed return on your contribution, so grabbing the full match usually comes before any other savings goal.
2026 contribution limits and how to max out
For 2026 the elective deferral limit is $24,500, or $32,500 if you are age 50 or older and using the catch-up. The calculator turns that into a percentage of your salary so you can see the rate that reaches the cap, and it stops the modeled contribution once you hit the limit rather than pretending you can defer past it. Want to weigh traditional against Roth, save job-offer profiles, or get exact per-state withholding? Download the Stub44 Salary Calculator app. For related paycheck questions, try the Net to Gross Salary Calculator, the Second Job Take-Home Calculator, or the Two-Income Household Take-Home Pay Calculator.
Frequently Asked Questions
Common questions about 401(k) paycheck impact calculator
How much will contributing to my 401(k) actually lower my paycheck?
Less than the amount you contribute, because traditional 401(k) money comes out before federal and state income tax. If you defer $100 and your combined income-tax rate is around 22 percent, your check only drops by roughly $78. That difference is the tax you no longer pay on the deferred dollars. Enter your salary and contribution rate above to see your exact paycheck delta and net cost per dollar.
Why does my take-home only drop by less than the amount I contribute?
Traditional deferrals lower your taxable wages, so payroll withholds less income tax from that check. Your paycheck reduction equals the contribution minus the income tax you no longer owe on it. The higher your bracket, the smaller the hit to your check for the same contribution, which is why the same 6 percent costs a high earner less out of pocket than a low earner.
Do 401(k) contributions reduce my Social Security and Medicare (FICA) taxes?
No. Elective 401(k) deferrals are excluded from federal income tax withholding but stay subject to Social Security (6.2 percent) and Medicare (1.45 percent). FICA is charged on your full gross wages, so contributing does not lower it. Your tax savings come only from income tax, not your full marginal rate, and your future Social Security benefit base is unaffected.
What is the 2026 401(k) contribution limit, and what percentage do I need to max it out?
The 2026 elective deferral limit is $24,500, rising to $32,500 if you are age 50 or older. Divide the limit by your salary to find the percentage needed: at $75,000 you would contribute about 32.7 percent to reach $24,500. The calculator reports your exact "rate to max out" once you enter your salary and check the age-50 box if it applies.
How does employer matching work, and how much free money am I leaving on the table?
A common formula is "50 percent up to 6 percent," meaning your employer adds 50 cents for every dollar you contribute, on contributions up to 6 percent of your pay. If you contribute below that cap, you forfeit part of the match. The tool shows match captured versus match forfeited, so you can see the guaranteed return you are passing up.
What is the difference between a traditional (pre-tax) and a Roth 401(k) for my paycheck?
Traditional contributions are pre-tax, so they lower this paycheck's income tax and your take-home drops by less than you contribute. Roth contributions are post-tax: there is no upfront tax break, so your check drops by the full contribution amount and the net cost per dollar is $1.00. This tool models traditional. To compare traditional and Roth side by side, model it in the Stub44 Salary Calculator app.
Does a 401(k) contribution lower my state income tax too?
In almost every state that taxes wages, yes. Traditional deferrals reduce state taxable wages the same way they reduce federal wages, so your state savings stack on top of the federal savings. States with no wage income tax, such as Texas and Florida, offer no state saving. To see how a move changes the picture, use the State Relocation Take-Home Comparison Calculator.
What contribution percentage should I choose to at least get my full employer match?
Set your contribution to at least your plan's match limit percentage. If the plan matches up to 6 percent of pay, contributing 6 percent captures the entire match, while anything less forfeits part of it. That match is an immediate guaranteed return, so most people fund up to the cap first, then raise the rate toward the annual limit as their budget allows.