Capital Gains Tax Calculator
Selling an asset for a profit? See the tax before you pull the trigger
Sell a stock, a rental, or a coin position that has appreciated, and the profit is not entirely yours to keep — a slice goes to capital gains tax. How big that slice is turns on two things you control more than you might expect: your cost basis (what you actually put in, not just the sticker purchase price) and how long you held the asset. This calculator takes the numbers from a specific sale — purchase price, sale price, the fees on both ends, any loss carryovers, a home-sale exclusion, and your holding period — and works out the taxable gain and the tax at short-term or long-term federal rates, plus a state rate if you add one.
Use it for a quick, educational estimate before you place a trade, sell a rental, or plan a home sale. The actual tax you owe will depend on your full tax situation and current law, so always confirm with a tax professional or official guidance.
What is a capital gain?
A capital gain is the profit you make when you sell a capital asset for more than your cost basis. Common capital assets include stocks, ETFs, mutual funds, bonds, rental property, your primary home, cryptocurrency, and collectibles.
In simple terms:
- You have a capital gain if your net sale proceeds are higher than what you invested, after adjusting for eligible costs and improvements.
- You have a capital loss if your net sale proceeds are lower than your adjusted investment.
Tax rules typically treat capital gains differently from wages or salary. Short-term gains are usually taxed at your ordinary income rate, while long-term gains often benefit from reduced tax rates.
Core formulas used in the calculator
This calculator follows a simplified version of common capital gains tax formulas. The basic steps are:
- Compute your adjusted basis.
- Compute your net proceeds from the sale.
- Find your capital gain or loss.
- Apply any loss carryovers and home sale exclusion.
- Multiply the taxable gain by your federal and state rates.
Adjusted basis
Your adjusted basis is your original purchase price plus certain purchase expenses and improvements.
In plain notation:
Adjusted basis = Purchase price + Purchase expenses / improvements
Net proceeds
Net proceeds are what you effectively receive after subtracting selling costs such as broker commissions, real estate agent commissions, and transfer fees.
Net proceeds = Sale price - Selling expenses
Capital gain before exclusions
Your preliminary gain (or loss) is:
Taxable gain after adjustments
Next, the calculator subtracts capital loss carryovers and any home sale exclusion amount you enter (for example, up to $250,000 for a qualifying single taxpayer or $500,000 for certain married couples filing jointly on a primary residence, subject to IRS rules).
In simplified form:
Taxable gain = max( 0, Gain - Loss carryover - Home sale exclusion )
Estimated tax owed
Finally, the calculator multiplies the taxable gain by your short-term or long-term federal rate, plus the state rate (if you enter one):
where r is your federal rate (short-term or long-term, as appropriate) and s is your state rate. Rates are entered as percentages in the calculator and converted to decimals in the math.
How to use this Capital Gains Tax Calculator
- Enter purchase information
- Purchase Price: What you originally paid for the asset.
- Purchase expenses/improvements: Include broker commissions on purchase, closing costs on a property, and qualifying capital improvements.
- Purchase date (optional): The date you acquired the asset.
- Enter sale information
- Sale Price: The gross amount you receive when you sell.
- Selling expenses: Broker commissions, listing fees, escrow fees, transfer taxes, and similar costs.
- Sale date (optional): The date you sell the asset.
- Holding period (years): If you do not enter exact dates, you can enter your approximate holding period here. A value at or below one year typically indicates short-term; over one year indicates long-term.
- Adjust for special items
- Capital loss carryover: Prior-year net capital losses you have not yet used on your tax return.
- Home sale exclusion amount: For a qualifying sale of a primary residence, enter the amount of gain you expect to exclude (for example, $250,000 or $500,000, subject to IRS rules).
- Enter filing status and income
- Filing status: Single, Married filing jointly, Married filing separately, or Head of household.
- Taxable income before this sale: Your estimated taxable income from all other sources, which helps you select appropriate federal long-term capital gains brackets if you are comparing rates.
- Specify tax rates
- Short-Term Federal Rate: An estimate of your marginal ordinary income tax rate.
- Long-Term Federal Rate: An estimate of your long-term capital gains rate based on your income and filing status.
- State tax rate: Your state marginal rate on capital gains, if applicable.
- Run the calculation
- Click Calculate to see your estimated taxable gain, total tax, and after-tax proceeds.
- Use Copy Results to keep a record or share the estimate with a financial or tax advisor.
Reading the estimate: gain, tax bill, and what you keep
The results table walks the sale from raw profit down to cash in hand, but three numbers carry most of the weight:
- Taxable gain after adjustments: what is left of your profit once basis, fees, loss carryovers, and any home-sale exclusion have been subtracted. This is the figure the tax rates actually bite into — not the headline gain.
- Total tax owed: federal tax at the short- or long-term rate plus state tax, if you entered one. The tool also shows the combined effective rate so you can see the two layers stacked together.
- Net proceeds after tax: the sale price minus selling costs and the tax — the cash that actually reaches your account.
Notice that the calculator picks the federal rate for you from the built-in brackets based on your filing status and income, but it defers to a rate you type in yourself. So if you leave the long-term rate untouched, you see the bracket the tool thinks you fall into; type over it and the tool honors your number and notes the default alongside it. That makes it easy to sanity-check whether a large sale would push part of your gain from the 15% into the 20% bracket.
If the gain comes out at zero or below, you have a capital loss rather than a gain, and there is no tax to compute on this sale. Losses can offset other gains and, within limits, ordinary income — the loss-carryover field is where you feed in unused losses from prior years and watch them shrink this year's taxable gain.
A few what-if moves the tool makes easy:
- Change the holding period from less than one year to more than one year to see the difference between short-term and long-term rates.
- Adjust the state rate to compare moving or selling while living in a different state.
- Modify the loss carryover field to see how fully using losses affects your tax bill.
Walking one sale through the math
Numbers make the steps concrete. Say Maya bought a stock position for $12,000 and paid $50 in brokerage fees on the way in. Two years later she sells the whole position for $20,000, paying $100 in commissions on the way out. She still has $2,000 of capital losses carried over from a bad year, her state taxes gains at 5%, and her income puts her in the 15% long-term federal bracket. Because she held for more than a year, the gain is long-term. Here is how the calculator gets from those inputs to her take-home:
Step-by-step:
- Adjusted basis
- Purchase price: $12,000
- Purchase expenses: $50
- Adjusted basis = $12,000 + $50 = $12,050
- Net proceeds
- Sale price: $20,000
- Selling expenses: $100
- Net proceeds = $20,000 - $100 = $19,900
- Capital gain before exclusions
- Gain = $19,900 - $12,050 = $7,850
- Apply loss carryover
- Loss carryover: $2,000
- Home sale exclusion: $0 (not a primary residence)
- Taxable gain = $7,850 - $2,000 = $5,850
- Compute tax
- Federal long-term rate: 15% (0.15)
- State rate: 5% (0.05)
- Total rate = 0.15 + 0.05 = 0.20 (20%)
- Estimated tax = $5,850 × 0.20 = $1,170
- After-tax proceeds
- Net proceeds: $19,900
- Estimated tax: $1,170
- After-tax proceeds = $19,900 - $1,170 = $18,730
By changing the rates or the holding period in the calculator, the investor can see how much more tax she would pay if the same gain were short-term instead of long-term.
Comparison: short-term vs. long-term capital gains
The table below summarizes some high-level differences between short-term and long-term capital gains treatment in the U.S. federal system. Exact details depend on your filing status, income, and current law.
| Feature | Short-Term Capital Gains | Long-Term Capital Gains |
|---|---|---|
| Holding period requirement | One year or less | More than one year |
| Typical federal tax rate | Ordinary income tax brackets (up to the top marginal rate) | Preferential 0%, 15%, or 20% brackets for most assets |
| Common examples | Frequent stock trades, crypto trades within a year | Long-term investments held for growth, many real estate holdings |
| Impact of taxable income | Directly uses your ordinary income bracket | Uses special long-term capital gains brackets based on income and filing status |
| Planning opportunities | Timing sales to avoid pushing into a higher ordinary bracket | Waiting to cross the one-year mark, managing income to qualify for lower LTCG brackets |
Where this estimate stops (and real returns pick up)
A clean estimate is only as honest as the corners it admits to cutting. This tool deliberately keeps the model simple, which means it skips a fair amount of the real tax code. Keep these gaps in mind before you treat a number here as final:
- Not personalized tax advice: Results are estimates only and do not replace advice from a CPA, EA, or other qualified professional.
- User-supplied tax rates: The calculator relies on the federal and state tax rates you enter. It does not automatically look up current IRS brackets or state rules.
- Single-asset focus: The tool focuses on one sale at a time. It does not automatically net multiple gains and losses across different assets for the same year.
- Simplified state tax treatment: State tax is modeled as a flat percentage applied to your taxable gain. Many states have more complex rules.
- No special asset classes: It does not explicitly model collectibles tax rates, depreciation recapture, Section 1250 property rules, qualified small business stock exclusions, or other specialized regimes.
- No wash sale or straddle rules: For stocks and other securities, the calculator does not apply wash sale rules, constructive sales, or straddle rules that can affect basis and recognized loss.
- No 3.8% Net Investment Income Tax (NIIT): The potential additional 3.8% surtax on net investment income for higher-income taxpayers is not included.
- No Alternative Minimum Tax (AMT): The tool does not compute AMT or interact with AMT rules.
- Home sale exclusion entered manually: For primary residence sales, you must enter the exclusion amount yourself. The calculator does not test your eligibility or automatically cap the exclusion at statutory limits.
- Approximate holding period: If you rely on the holding period in years instead of exact dates, the classification as short-term vs. long-term is approximate for planning scenarios only.
Because tax law changes periodically, numbers and examples may no longer match current rules. Always verify important decisions with up-to-date official sources, such as IRS publications, and with a qualified professional.
Short-term vs. long-term capital gains
The holding period - how long you held the asset - determines whether your gain is short-term or long-term.
- Short-term capital gain: Asset held for one year or less. Taxed at your ordinary federal income tax rate (the same brackets used for wages).
- Long-term capital gain: Asset held for more than one year. Taxed at reduced long-term capital gains rates (commonly 0%, 15%, or 20% at the federal level, depending on income and filing status).
This calculator lets you indicate the holding period using either:
- Purchase date and sale date, or
- Holding period (years) if you prefer to enter an approximate duration.
If you provide both exact dates and a holding period in years, treat the dates as your primary reference for real tax reporting. The holding period field is provided mainly for planning and what-if analysis.