About the Federal Income Tax Calculator
The U.S. uses a progressive system: each slice of taxable income is taxed at the rate for its bracket. Moving into a higher bracket only affects the income inside that bracket, not everything you earn.
Brackets and standard deductions are published by the IRS for each year and stored centrally with an explicit year, so an estimate for 2025 always uses 2025 figures.
How It Works
Taxable income is your annual income minus adjustments (such as deductible IRA contributions) minus either the standard deduction for your filing status or your itemized deductions.
Tax is calculated bracket by bracket, then reduced by the credits you enter (not below zero). The effective rate divides the tax by your total income; the marginal rate is the rate on your last dollar of taxable income.
Formula
Example
A single filer with $100,000 of wages takes the 2026 standard deduction and has no credits.
Inputs
- Income
- $100,000
- Standard deduction
- $16,100
- Filing status
- Single
Results
- Taxable income
- $83,900.00
- Estimated tax
- $13,170.00
- Effective rate
- 13.17%
- Marginal rate
- 22.00%
The first $12,400 is taxed at 10%, the next $38,000 at 12%, and the remaining $33,500 at 22%: $1,240 + $4,560 + $7,370 = $13,170.
Assumptions & Limitations
- Ordinary income only: qualified dividends and long-term capital gains (which have their own rates) are not separated — use the Capital Gains Tax Calculator for those.
- Credits are nonrefundable in this estimate, so tax cannot go below $0.
- Not included: additional standard deductions for age 65+ or blindness, the alternative minimum tax, self-employment tax, and state taxes.
- Data: 2025 brackets from IRS Rev. Proc. 2024-40 with the standard deduction as amended in 2025; 2026 from IRS Rev. Proc. 2025-32.
Understanding Your Results
- Marginal Tax Rate: The rate on your next dollar of taxable income — useful for judging the effect of a raise or a deduction.
- Effective Tax Rate: Your overall average rate, always lower than the marginal rate in a progressive system.
- Bracket chart: How much of your taxable income falls into each bracket and the tax on it.