Why do pre-tax deductions save money?

Because they lower the income that is taxed. A $500 traditional 401(k) contribution in the 22% bracket reduces your taxes by about $110, so it only costs you about $390 of take-home to save $500 for retirement.

What is the difference between pre-tax and post-tax deductions?

Pre-tax deductions (traditional 401(k), HSA, most insurance premiums) come out before taxes are figured, reducing taxable income. Post-tax deductions (Roth 401(k), garnishments, some benefits) come out after taxes and do not reduce your tax.

What tax rate should I enter?

Use your combined effective rate — federal income tax plus Social Security (6.2%), Medicare (1.45%), and any state/local income tax — as a share of taxable pay. Many workers land somewhere around 20–30%. For accuracy, check a recent pay stub.

Why is my real paycheck different?

This uses one flat rate, but actual withholding is progressive and depends on filing status, W-4 settings, the Social Security wage cap, pre-tax benefit specifics, and state rules. Treat the result as a close estimate, not exact.

How do I get an annual figure?

Multiply net per-period pay by the number of periods: 26 for biweekly, 24 for semi-monthly, 12 for monthly, 52 for weekly. The hint shows a biweekly-annual example.

Why do pre-tax deductions save money?

Because they lower the income that is taxed. A $500 traditional 401(k) contribution in the 22% bracket reduces your taxes by about $110, so it only costs you about $390 of take-home to save $500 for retirement.

What is the difference between pre-tax and post-tax deductions?

Pre-tax deductions (traditional 401(k), HSA, most insurance premiums) come out before taxes are figured, reducing taxable income. Post-tax deductions (Roth 401(k), garnishments, some benefits) come out after taxes and do not reduce your tax.

What tax rate should I enter?

Use your combined effective rate — federal income tax plus Social Security (6.2%), Medicare (1.45%), and any state/local income tax — as a share of taxable pay. Many workers land somewhere around 20–30%. For accuracy, check a recent pay stub.

Why is my real paycheck different?

This uses one flat rate, but actual withholding is progressive and depends on filing status, W-4 settings, the Social Security wage cap, pre-tax benefit specifics, and state rules. Treat the result as a close estimate, not exact.

How do I get an annual figure?

Multiply net per-period pay by the number of periods: 26 for biweekly, 24 for semi-monthly, 12 for monthly, 52 for weekly. The hint shows a biweekly-annual example.

Net Pay Calculator (Take-Home After Deductions)

Estimate take-home pay from gross pay after pre-tax deductions (401(k), HSA, insurance), income tax, and other withholdings.

Result

Net take-home pay

$3,237.00

64.7% of gross · $84,162.00 if biweekly/yr

Gross pay$5,000.00
401(k) contribution− $500.00
HSA/FSA− $200.00
Insurance premiums− $150.00
Taxable pay$4,150.00
Income + payroll tax (22%)− $913.00
Other (post-tax)− $0.00
Net pay$3,237.00

Source: Pre-tax deductions reduce taxable pay; tax applies to the remainder; post-tax items are subtracted last. Net = gross − pretax − tax − post-tax.

Not financial advice — A simplified estimate using one combined tax rate. Real withholding depends on filing status, allowances, Social Security/Medicare caps, and state rules. Use the IRS Tax Withholding Estimator for precision.

Step-by-step

Pre-tax deductions = 401(k) $500.00 + HSA $200.00 + insurance $150.00 = $850.00.
Taxable pay = $5,000.00 − $850.00 = $4,150.00; tax = × 22% = $913.00.
Net = gross − pre-tax − tax − other = $3,237.00.

How to use this calculator

Enter your gross pay for one pay period.
Enter your 401(k) percentage and HSA/FSA and insurance amounts (pre-tax).
Enter your combined effective tax rate.
Add any post-tax deductions, then read your net take-home pay.

About this calculator

Your take-home pay is what is left after deductions are pulled from your gross paycheck, and the order matters. Pre-tax deductions — traditional 401(k) contributions, HSA or FSA contributions, and most health insurance premiums — come out first and reduce the income that gets taxed, which is part of why they are valuable. Income and payroll taxes are then calculated on the reduced (taxable) amount. Finally, any post-tax deductions like Roth 401(k) contributions or wage garnishments are subtracted. This calculator follows that sequence using a single combined tax rate you supply, and reports your net pay both as a dollar amount and as a percentage of gross. For a precise figure, the real withholding depends on your filing status, the Social Security wage cap, and state taxes — the IRS Tax Withholding Estimator handles those details.

How it works — the formula

Pre-tax = 401(k)% × gross + HSA + insurance
Taxable = gross − pre-tax
Tax = taxable × rate
Net = gross − pre-tax − tax − post-tax

Pre-tax items shrink the taxable base; tax is applied to what remains; post-tax items are removed last.

Source: IRS — Tax Withholding Estimator

Worked examples

Example 1

$5,000, 10% 401k, $200 HSA, $150 ins, 22%

Inputs:: gross=5000, retirement=10, hsa=200, insurance=150, taxRate=22
Output:: taxable $4,150, tax $913, net $3,237

Example 2

$3,000, no pre-tax, 18% tax

Inputs:: gross=3000, retirement=0, hsa=0, insurance=0, taxRate=18
Output:: net $2,460

Example 3

$6,000, 15% 401k, $300 HSA, 24%

Inputs:: gross=6000, retirement=15, hsa=300, insurance=0, taxRate=24
Output:: taxable $4,800, net ~$3,648

Limitations

Single flat tax rate, not progressive brackets.
Ignores Social Security wage cap and filing-status nuances.
State/local specifics vary; use the IRS estimator for precision.

Estimate; actual withholding depends on your W-4, status, and locale.

Frequently asked

Subtract pre-tax deductions (401(k), HSA, insurance) from gross to get taxable pay, apply your tax rate to that, then subtract the tax and any post-tax deductions. Net = gross − pre-tax − tax − post-tax.