How the Paycheck Calculator Works

One calculation engine produces every number on this site, from the paycheck calculator to the salary tables on each state page. This page writes out what it does so you can check it against a pay stub.

Gross pay

salary:  gross a year = salary
hourly:  gross a year = hourly wage x hours a week x 52
one paycheck = gross a year / paychecks a year (52, 26, 24 or 12)

Pre-tax deductions

• Traditional 401(k): a percent of gross pay, capped at the $24,500 2026 limit. It lowers federal and most state taxable wages, but not Social Security or Medicare wages.
• Health, dental and vision premiums and HSA contributions through payroll: they lower federal, Social Security, Medicare and state taxable wages.
• After-tax deductions such as a Roth 401(k) come out last and do not change any tax.

Federal income tax withholding

The calculator uses the annual percentage method for Forms W-4 from 2020 or later, from IRS Publication 15-T (2026), Worksheet 1A.

adjusted wages = federal taxable wages a year + W-4 Step 4(a) - W-4 Step 4(b)
tax            = 2026 rate schedule applied to (adjusted wages - standard deduction)
withholding    = max(0, tax - W-4 Step 3 credits) / paychecks + W-4 Step 4(c)

The IRS tables subtract $8,600 ($12,900 for married filing jointly) on the worksheet and start their brackets at the rest of the standard deduction. Subtracting the full $16,100 standard deduction gives the same result. When the W-4 Step 2 box is checked, the tables use half the brackets and half the standard deduction, and so does the calculator.

Social Security and Medicare

Social Security = 6.2% x min(wages, $184,500)
Medicare        = 1.45% x wages + 0.9% x wages over $200,000

Social Security and Medicare wages exclude section 125 premiums and HSA contributions but include 401(k) contributions. Wage base: Social Security Administration.

State income tax

State tax is the year's tax on state taxable wages, spread evenly over your paychecks. For each state the calculator subtracts the standard deduction and personal exemptions for your filing status, applies the 2026 brackets or flat rate, and subtracts personal and dependent credits. States with special rules, such as a federal tax deduction or a phase-out of low brackets for high earners, are handled one by one. Each state page links to the state's own source.

States publish their own withholding formulas. Most are built to collect this same year's tax, so the estimate lands close to a real paycheck. A few states withhold on simplified tables that can differ by a few dollars a check.

State payroll deductions

Disability insurance, paid family leave and similar programs are applied at each state's 2026 employee rate and wage limit: California SDI, New York disability and paid family leave, New Jersey, Rhode Island and Hawaii disability insurance, paid leave in Washington, Massachusetts, Oregon, Colorado, Connecticut, Delaware, Minnesota and Maine, WA Cares, the Oregon transit tax, and employee unemployment tax in Alaska, New Jersey and Pennsylvania.

What the calculator assumes

• Pay is the same every paycheck for the whole year.
• You live and work in the same state.
• Local income taxes are not included. State pages describe them where they apply.
• Bonuses and other supplemental wages are not included. Employers often withhold a flat 22% federal rate on those.
• Results are rounded to the cent for display only.