Taxes
Capital Gains Tax Calculator
Holding an asset for more than a year usually changes its tax rate, not just its return. Long-term gains are taxed at 0%, 15%, or 20% for most people; sell a day early and the whole gain is taxed as ordinary income.
Formula shown below · Tested against worked examplesHow we verify
What you paid, including commissions and fees.
Estimated tax owed: $3,000
Estimated tax owed
$3,000
Federal capital gains tax at the rate you selected.
- Capital gain
- $20,000
- You keep
- $67,000
- Tax as a share of the gain
- 15%
Compare scenariosTry three values of one input
| Purchase price (cost basis) | |||
|---|---|---|---|
| Estimated tax owed | $3,750 | $3,000−$750 | $2,250−$1,500 |
| Capital gain | $25,000 | $20,000−$5,000 | $15,000−$10,000 |
| You keep | $66,250 | $67,000+$750 | $67,750+$1,500 |
Every other input stays at the value you set above — currently $50,000 for purchase price (cost basis). Differences are measured against the first column.
Saved scenariosSave this calculation
Saved in this browser only — no account, and nothing is sent to us. Clearing your browser data deletes them.
How this calculator works
Gain = sale price − cost basis. Tax = gain × the rate you select, and nothing is owed on a loss. The effective rate divides tax by the gain, and 'you keep' is the sale price less the tax.
Federal only, with a single flat rate you choose — real liability depends on your total income, filing status, state, and the 3.8% net investment income tax. It also does not model losses carried forward or the primary-residence exclusion, which shelters up to $250,000 of gain ($500,000 married) on a home you lived in.
Formula
Gain = Sale price − Cost basis
Tax = max(0, Gain) × t
Net proceeds = Sale price − Tax- Cost basis
- What you paid, PLUS reinvested dividends and commissions
- t
- The rate for your holding period and income
A loss produces no tax here and may be usable against other gains. Omitting reinvested dividends from the basis is the most common error, and it overstates both the gain and the tax.
What this assumes
- The holding period decides the rate: more than a year is long-term, anything less is taxed as ordinary income.
- Long-term rates of 0%, 15% or 20% depending on income. The net investment income tax and state capital gains tax are not included.
- Cost basis as entered. Reinvested dividends increase basis and are commonly omitted, which overstates the gain.
What changes this number
- Holding period
- Crossing one year can halve the tax on the same gain. It is the cheapest planning decision available.
- Your income that year
- The 0% long-term band is real and useful in a low-income year — a career break, or early retirement.
- Which lots you sell
- Specifying high-basis shares rather than accepting first-in-first-out reduces the gain directly.
A worked example
Take the $20k long-term gain at 15% scenario. These figures are produced by the calculator above, not written alongside it, so they always match what the tool returns.
What you enter
- Purchase price (cost basis)
- $50,000
- Sale price
- $70,000
- Your capital gains rate
- 15% — long-term, most filers
What it returns
- Estimated tax owed
- $3,000
- Capital gain
- $20,000
- You keep
- $67,000
- Tax as a share of the gain
- 15%
Sources
This calculator uses no external data — the result follows entirely from the formula above and the values you enter, so there is nothing to cite beyond the arithmetic.
Calculator last reviewed August 9, 2026. How we verify
Try an example
Frequently asked questions
What's the difference between short-term and long-term gains?
The holding period. Sell an asset you have owned a year or less and the gain is short-term, taxed at your ordinary income rate — up to 37%. Hold longer than a year and it becomes long-term, taxed at 0%, 15%, or 20% depending on income. Waiting a few extra days can be the highest-paid decision of the year.
What is cost basis?
What you paid, adjusted — purchase price plus commissions and fees, and for property, plus capital improvements. A higher basis means a smaller taxable gain, which is why keeping records of improvements and reinvested dividends matters. Brokerages track basis for most securities.
Do I owe state tax too?
Usually. Most states tax capital gains as ordinary income, and a handful do not tax income at all. This calculator covers the federal portion only, so add your state rate for the full picture — our state income tax pages list them.
What about the 3.8% net investment income tax?
It applies on top of the rates above once modified adjusted gross income passes $200,000 single or $250,000 married filing jointly. It is not included here; if you are near those thresholds, add it to the rate you select or ask a tax professional.
Can I use losses to reduce the tax?
Yes. Capital losses offset capital gains dollar for dollar, and up to $3,000 of leftover loss can offset ordinary income each year, with the rest carried forward. Deliberately realising losses to offset gains is called tax-loss harvesting — watch the 30-day wash-sale rule.
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Disclaimer: DayCents provides this calculator for educational purposes only. Results are estimates based on your inputs and the stated assumptions — they are not financial advice, a quote, or an offer of credit. Consult a qualified financial professional before making major money decisions.