How the Income Tax Calculator Works
Federal income tax in the United States is progressive. That means you do not pay one rate on all of your income. Your income is split into slices, and each slice is taxed at its own rate. The first slice is taxed at the lowest rate, and only the money that falls into a higher slice is taxed at the higher rate. The Income Tax Calculator applies these rules to your numbers, and shows the tax slice by slice.
What you enter
- Income before tax: your yearly wages and other taxable income.
- Filing status: single, married filing jointly, or head of household. Each has its own bracket sizes and its own standard deduction.
- Pre-tax contributions: money you put into a traditional 401(k), traditional IRA, HSA or similar account. It lowers your taxable income.
- Deduction: the standard deduction, or the total of your itemized deductions, such as mortgage interest, state and local taxes and gifts to charity.
- Tax credits: amounts that reduce your tax directly, such as the child tax credit.
- State tax rate: a flat estimate of your state income tax. Use 0 if your state has none.
Step by step
income after pre-tax contributions = income - pre-tax contributions taxable income = that amount - deduction (never below zero) federal tax = the sum of each slice of taxable income x its rate, minus credits
The calculator uses the 2025 federal brackets, and the standard deduction of $15,750 for a single filer, $31,500 for a married couple filing jointly and $23,625 for a head of household. The single brackets are:
| Taxable income | Rate |
|---|---|
| Up to $11,925 | 10% |
| $11,925 to $48,475 | 12% |
| $48,475 to $103,350 | 22% |
| $103,350 to $197,300 | 24% |
| $197,300 to $250,525 | 32% |
| $250,525 to $626,350 | 35% |
| Over $626,350 | 37% |
A worked example
A single filer earns $75,000, with no pre-tax contributions, and takes the standard deduction. Taxable income is $75,000 - $15,750 = $59,250.
| Bracket | Rate | Income in it | Tax |
|---|---|---|---|
| Up to $11,925 | 10% | $11,925 | $1,192.50 |
| $11,925 to $48,475 | 12% | $36,550 | $4,386.00 |
| $48,475 to $103,350 | 22% | $10,775 | $2,370.50 |
| Total | $59,250 | $7,949.00 |
The tax is $7,949. The top bracket reached is 22%, but the average rate on the whole $75,000 of income is only 10.6%. After this tax, $67,051 is left. A flat 22% on the taxable income would give $13,035, which is far too high. That is why the calculator works slice by slice.
Chart: the income in each bracket
The same example. The bar shows how much of the taxable income falls in each bracket:
10% █████████████ $11,925 12% ████████████████████████████████████████ $36,550 22% ████████████ $10,775
What changes the tax
| Change to the example | Federal tax |
|---|---|
| None (single, standard deduction) | $7,949 |
| $6,000 into a traditional 401(k) | $6,629 |
| Head of household instead of single | $5,825 |
| Itemized deductions of $30,000 | $5,161.50 |
| A $2,000 tax credit | $5,949 |
A deduction lowers your taxable income, so its value depends on your bracket. A credit lowers the tax itself, dollar for dollar, so a $2,000 credit saves $2,000, while a $2,000 deduction saves only $440 at the 22% rate.
Marginal and effective rate
- Marginal rate: the rate on your last dollar of taxable income. It tells you how much tax you would pay on a raise, or save on a deduction.
- Effective rate: your total tax divided by your total income. It is what you really pay on average, and it is always lower than the marginal rate.
What this calculator does not include
- Social Security and Medicare tax, which are separate from income tax.
- Long-term capital gains and qualified dividends, which have their own lower rates.
- The alternative minimum tax, self-employment tax, the net investment income tax, and phase-outs of credits and deductions.
- State tax rules. The state tax is a flat estimate, and real state taxes have their own brackets and deductions.
- Changes in the tax law. The figures are for 2025, so check irs.gov for the current year.
This tool gives an estimate for general information only. It is not tax advice. For your own situation, talk to a qualified tax professional.