How the math works
We aim for clarity over complexity. Here's exactly what's calculated and what's not.
1 · Gross pay
For salaried workers, this is your annual salary. For hourly, it's rate × hours × 52, with optional 1.5× overtime for hours over 40 per week.
2 · Pre-tax deductions
401(k) and health-insurance premiums are subtracted from gross pay before income tax is calculated. 401(k) accepts a percentage of gross or a flat dollar amount per paycheck.
3 · Federal income tax
Calculated using the 2024 IRS marginal brackets for your filing status, after the standard deduction ($14,600 single / $29,200 married / $21,900 head of household).
4 · FICA (Social Security + Medicare)
Social Security: 6.2% on wages up to the 2024 wage base of $168,600. Medicare: 1.45% on all wages, plus an additional 0.9% on wages above $200,000 ($250,000 if married).
5 · State income tax
Uses approximate 2024 state brackets for all 50 states + DC. No-income-tax states (AK, FL, NV, NH, SD, TN, TX, WA, WY) return zero.
What's not included
Local/city taxes, state SDI/SUI, post-tax deductions, tax credits (EITC, child tax credit), and itemized deductions. This is a strong estimate, not a tax return.
Sources & references
All tax data is drawn from primary US government sources for the 2024 tax year:
- IRS — 2024 federal income tax brackets
- IRS Publication 501 — Standard deduction amounts
- SSA — 2024 Social Security wage base ($168,600)
- IRS Topic 560 — Additional Medicare Tax (0.9% over $200k)
- State income tax brackets compiled from each state department of revenue's 2024 published rate schedules.
Last reviewed: April 2025. Tax law changes; verify against the latest IRS guidance before making decisions.