Gross to Net Calculator — the full deduction waterfall, itemized

The gross to net calculator exists to answer a question your regular paycheck stub answers badly: not "what did I get paid" but "in what order did my money disappear, and which of those deductions actually saved me tax?" Most take-home-pay tools flatten everything into one lump withholding number. This one doesn't. It walks the money through the waterfall step by step — gross salary, minus pre-tax deductions, equals taxable income, minus federal tax, minus FICA, minus state tax, minus post-tax deductions, equals net pay — because the order genuinely changes the math, not just the presentation.

Arb Digital built this as a benefits-election tool, not a payday tool. It's meant for the moment during open enrollment when you're staring at a 401(k) contribution slider or a health plan menu and trying to figure out what a 1% change actually costs you out of pocket. Spoiler: it's less than 1% of your paycheck, because pre-tax money is subsidized by the tax code before it ever leaves your gross pay.

What the Gross to Net Calculator Does

You enter your gross annual salary, your filing status, and then the deductions that make up your actual paycheck: a 401(k) percentage, an annual health insurance premium, an HSA or FSA contribution, and any other pre-tax deductions your employer offers (commuter benefits, group life insurance under $50,000 of coverage, and so on). Then you enter the post-tax side: Roth 401(k) contributions (which are funded with already-taxed dollars) and garnishments or union dues, which come out after tax withholding is calculated. Finally you enter a flat state income tax rate as a stand-in for your state's bracket system.

The calculator subtracts your pre-tax deductions from gross first, producing a "taxable income" figure. It applies a 2025 federal bracket estimate and FICA (Social Security and Medicare) to that reduced number — not to your full gross salary. Then it applies your state rate, also to the reduced taxable base. Only after all of that does it subtract your post-tax items. What's left is your net annual pay, broken into an annual total and, in the results grid, four supporting numbers: total pre-tax deductions, total tax paid, total post-tax deductions, and net pay as a percentage of gross.

How to Use It

1. Enter your gross annual salary. Use your full stated salary, not last year's take-home number.
2. Pick your filing status. Single, Married Filing Jointly, or Head of Household — this changes the standard deduction and bracket thresholds used in the federal estimate.
3. Fill in your 401(k) percentage and pre-tax deductions. This is the part most take-home calculators skip. Get your health premium and HSA/FSA numbers from your benefits portal or last pay stub.
4. Add any post-tax items. Roth 401(k) contributions and wage garnishments both reduce your net pay, but neither reduces your taxable income, so they're applied last.
5. Set your state tax rate. If you don't know your effective state rate, a rough estimate (or 0 for a no-income-tax state) is fine — this tool is built for planning, not filing.
6. Read the waterfall. Compare "total pre-tax deductions" against "total tax" to see how much of your paycheck reduction came from benefits versus taxes.

The Formula — Why Order Matters

Here's the part that makes this calculator different from a generic net-pay estimator: pre-tax deductions are subtracted from gross salary before federal tax, FICA, and state tax are calculated. That means a $100 contribution to your 401(k) doesn't cost you $100 of take-home pay — it costs you roughly $100 minus whatever tax bracket you're in. If you're in the 22% federal bracket plus a 5% state rate, that $100 contribution only reduces your paycheck by about $73, because the other $27 would have gone to taxes anyway. Roth 401(k) and garnishments work the opposite way: because they're subtracted after tax is calculated, a $100 Roth contribution costs you the full $100 of net pay, dollar for dollar.

The federal estimate here uses 2025 tax brackets and the 2025 standard deduction — $15,000 for single filers and $30,000 for Married Filing Jointly — applied to your taxable income after pre-tax deductions. FICA is calculated at 6.2% for Social Security up to the 2025 wage base of $176,100, plus 1.45% for Medicare with no cap. These are illustrative figures pulled from published guidance; see the IRS federal tax brackets page for the authoritative numbers and the Social Security Administration's contribution and benefit base for the FICA wage cap.

Why Pre-Tax Deductions Are a Discount, Not a Cost

Think of your 401(k) match conversation at open enrollment. A common hesitation is "I can't afford to put in more." But the waterfall shows that "putting in more" doesn't reduce your paycheck by the same amount you're contributing. If your marginal tax rate (federal plus state) is around 27%, then bumping your 401(k) contribution by $2,000 a year only reduces your net pay by roughly $1,460 — the other $540 is tax you would have paid anyway. That's the entire argument for maximizing pre-tax benefits before considering after-tax savings: the government is effectively subsidizing part of every pre-tax dollar you set aside, and that subsidy only shows up if you look at the waterfall in order.

The same logic applies to HSA and FSA elections. An HSA is arguably the most tax-advantaged pre-tax deduction available, because it also grows tax-free and can be withdrawn tax-free for qualified medical expenses — a triple tax advantage the IRS Publication 969 describes in detail. An FSA doesn't carry over as generously, but it still reduces this year's taxable income the same way. Health insurance premiums deducted pre-tax under a Section 125 cafeteria plan work identically — money that leaves your paycheck before FICA and income tax ever touch it.

Where Post-Tax Deductions Fit

Roth 401(k) contributions, wage garnishments, and after-tax union dues sit at the bottom of the waterfall for a structural reason: none of them change what the IRS or your state considers taxable. A Roth contribution is a savings decision made with money that's already been taxed, in exchange for tax-free withdrawals decades from now. A garnishment is a legal obligation that doesn't care what your tax bracket is. Because neither reduces taxable income, both come straight off net pay after every tax line has already been calculated — which is exactly why the calculator subtracts them last.

How This Differs From Arb Digital's Other Paycheck Tools

If you just want to know what lands in your bank account on a specific payday, our paycheck take-home calculator models the full per-paycheck picture. If you want the tax breakdown line by line for a single pay period, use the paycheck tax calculator. For a simple annual net figure without itemizing every benefit, the after-tax income calculator is faster. This tool is the only one built specifically around the itemized pre-tax vs. post-tax waterfall — use it when you're actually deciding how much to put into a 401(k), HSA, or FSA, not just checking your take-home pay.

• Use this tool during open enrollment or when adjusting your 401(k) contribution percentage.
• Use the paycheck take-home calculator for a realistic per-paycheck number including pay frequency.
• Use the income tax calculator if you want a full annual tax return style estimate rather than a paycheck-level view.

Common Mistakes to Avoid

• Comparing a Roth contribution dollar-for-dollar with a traditional 401(k) contribution. They cost different amounts of net pay for the same contribution amount — Roth costs the full dollar, traditional costs less after the tax discount.
• Forgetting employer-sponsored pre-tax health premiums when estimating take-home pay. These often run $3,000–$6,000+ a year and materially shrink taxable income.
• Using your marginal tax rate instead of your effective rate when eyeballing "what will this cost me." The waterfall calculates it properly; a back-of-envelope guess usually doesn't.
• Ignoring the FICA wage base cap. Very high earners stop paying the 6.2% Social Security portion once wages exceed the annual cap, which changes their true marginal deduction rate.
• Treating an FSA like an HSA. FSAs are largely "use it or lose it" each plan year with limited carryover, while HSAs roll over indefinitely and stay with you between jobs.

Related Free Tools From Arb Digital

Pair this waterfall view with the paycheck take-home calculator for a real per-payday number, the paycheck tax calculator for a per-period tax breakdown, the after-tax income calculator for a quick annual net figure, and the income tax calculator for a full annual tax estimate. If you're weighing a job offer in a different state, the take home pay by state calculator shows how state tax alone changes the picture. Browse everything else in our free online tools hub.

Frequently Asked Questions

This tool provides general estimates for educational purposes only and is not financial, tax, legal, or medical advice. Figures are illustrative; consult a licensed professional for decisions.