Paycheck After 401k Calculator
Contributing to a traditional 401k lowers your take-home pay, but by less than the contribution itself, because the money goes in before income tax is calculated. This calculator shows the net effect on a single paycheck. It first subtracts your pre-tax 401k contribution from gross pay, then applies your income tax rate to the reduced, taxable amount, and finally shows what lands in your pocket. Enter your gross pay, your contribution rate, and your effective income tax rate, and the tool returns your 401k contribution in dollars, the tax withheld, and your take-home pay. Seeing all three figures together makes the trade-off clear: a 6 percent contribution reduces a paycheck by less than 6 percent of gross, because contributing also shrinks the taxable wage. The rates are kept editable so you can model different contribution levels or tax situations. This is a simplified single-paycheck view that uses a flat tax rate and excludes Social Security, Medicare and state tax, which the IRS and your state apply separately. The IRS sets the federal 401k contribution limits and the pre-tax treatment. Every figure here is computed deterministically from the formula shown in full below, with a worked example that reconciles exactly to the calculator so you can follow each step.
A pre-tax 401k cuts taxable pay first: take-home = gross minus contribution minus tax on the rest. On $5,000 gross with a 6% contribution and 22% tax, take-home pay is $3,666.00.
Paycheck After 401k formula
Contribution = Gross x contribution rate
Taxable pay = Gross - Contribution
Tax = Taxable pay x tax rate
Take-home = Gross - Contribution - Tax
Because the contribution is pre-tax, it lowers the wage that tax is applied to, so a paycheck falls by less than the full contribution amount.
Worked example
Find the take-home pay on 5,000 gross with a 6% pre-tax 401k contribution and a 22% tax rate.
- Contribution: 5,000 x 6% = 300.00
- Taxable pay: 5,000 - 300 = 4,700
- Tax: 4,700 x 22% = 1,034.00
- Take-home: 5,000 - 300 - 1,034 = 3,666.00
These are the calculator's default inputs, so the result above matches the widget exactly.
Paycheck After 401k Calculator: frequently asked questions
How does a 401k lower my taxable pay?
Traditional 401k contributions are deducted from your wages before federal income tax is calculated, so the amount you contribute is not taxed in the year you earn it. Tax is deferred until you withdraw the money in retirement.
Why does my paycheck drop by less than my contribution?
Because contributing also reduces the wages that income tax is applied to. The tax you save on the contribution partly offsets the cash that leaves your paycheck, so net pay falls by less than the full contribution.
Does this include Social Security and Medicare?
No. This simplified view uses a single income tax rate. Social Security and Medicare (FICA) taxes still apply to 401k contributions and are calculated separately, as is state income tax.
What are the 401k contribution limits?
The IRS sets an annual elective deferral limit that is adjusted periodically, with an additional catch-up amount for workers age 50 and over. Check the current IRS limit before maximizing contributions.
What is the paycheck after 401k formula?
Take-home pay equals gross minus the contribution minus tax on the remaining wages. On 5,000 with a 6% contribution and 22% tax, take-home pay is 3,666.00.
Official sources
- US federal payroll, withholding and reimbursement guidance: US Internal Revenue Service (IRS). As at 25 June 2026.
Reviewed by the CalculatorHub team, edited by James Graham, 25 June 2026. See our methodology. This is general information, not financial, tax, legal or investment advice.