How we calculate

Full-time pay assumes 40 hours/week × 52 weeks = 2,080 hours/year. Hourly → annual multiplies by 2,080; annual → hourly divides by 2,080. Bi-weekly uses 26 pay periods, weekly 52, monthly 12. You can change hours and weeks for part-time or unpaid-leave schedules.

Brackets and the standard deduction come from IRS Revenue Procedure 2025-32 (single, married filing jointly, head of household). Tax is computed progressively on income after the standard deduction.

Social Security: 6.2% on wages up to the $184,500 wage base. Medicare: 1.45% on all wages, plus the 0.9% Additional Medicare Tax above $200,000 (single / head of household) or $250,000 (married filing jointly).

We model the income tax of all 50 states — graduated brackets, flat taxes, standard deductions, personal exemptions, and state-specific mechanisms like South Carolina's deduction phase-out, Utah's taxpayer credit, Oregon's federal-tax subtraction and California's SDI payroll levy (1.3%, no wage cap). Nine states (AK, FL, NV, NH, SD, TN, TX, WA, WY) levy no wage income tax. Each state's data comes from its own revenue department and is validated against published worked examples before it ships — a state engine that can't reproduce its source's $50k/$100k examples doesn't go live. We do not currently model local/city taxes (e.g. NYC), the California 1% surcharge over $1M, most credits, or itemized deductions.

KeepWage's calculator pages are generated programmatically from a single verified tax engine — the same code computes every page, so a correction to one rate fixes every affected page at once. The engine, its data and this methodology are written and maintained by people; page generation is automated on top of that human-verified data. We re-verify tax data when the IRS or a state publishes new figures, and log every data change in our changelog.

The full list — IRS revenue procedures plus the official tax authority for each of the 50 states — is on our data sources page. Key federal references:

• IRS Rev. Proc. 2025-32 — federal brackets & standard deduction
• IRS Topic 751 / 560 — FICA rates, wage base, Additional Medicare Tax
• SSA — Social Security contribution & benefit base
• State revenue departments — all 50 state engines (see /sources)

Tell us at /contact — accuracy reports are our highest-priority mail, and corrections are logged publicly in the changelog.