This US Federal Income Tax Calculator estimates what a W-2 earner owes the IRS in a year. It applies the progressive 2024 tax brackets to your income after the standard deduction, then adds FICA payroll taxes. Crucially, it shows both your marginal rate (the bracket of your last dollar) and your effective rate (total tax ÷ total income) so you can plan around real numbers, not headline percentages.
How it works
- Taxable income = gross wages − standard deduction ($14,600 single, $29,200 married filing jointly for 2024). Negative results are floored at $0.
- Federal income tax is computed bracket by bracket. Each slice of taxable income is taxed at its bracket rate — 10%, 12%, 22%, 24%, 32%, 35%, then 37% — and the slices are summed. This is why your effective rate is lower than your top bracket.
- FICA adds Social Security at 6.2% of wages up to the $168,600 wage base, Medicare at 1.45% on all wages, and a 0.9% Additional Medicare surtax on wages above $200,000 (single) or $250,000 (married).
Example
A single filer earning $80,000 in 2024: taxable income = $80,000 − $14,600 = $65,400. Tax fills the 10% bracket ($1,160), the 12% bracket ($4,266), and part of the 22% bracket, totalling roughly $9,500 in federal income tax. Add FICA ($6,120) and the combined burden is about $15,600 — an effective income-tax rate near 11.9%, well below the 22% marginal bracket.
Tips and notes
This estimate ignores tax credits (child tax credit, EITC), itemized deductions, retirement contributions, and non-wage income — all of which can move the number significantly. Use it for quick comparisons (for example two job offers) rather than filing. For your actual return, consult a tax professional or the IRS instructions.