Capital Gains Tax Calculator

Say you are a single filer with $80,000 of taxable income and you sell stock for a $50,000 long-term gain. That gain stacks on top of your income, landing in the 15% long-term bracket - so you owe about $7,500 in federal capital gains tax and keep $42,500. If you had instead sold after only six months, that same $50,000 would be a short-term gain taxed as ordinary income at your 22%-24% marginal rate, costing roughly $11,500. Holding a little longer can save thousands - which is exactly why this capital gains tax calculator separates short-term from long-term and shows the rate that actually applies. All figures here are for tax year 2025 (returns filed in 2026).

2025 long-term capital gains brackets

Long-term rates depend on your total taxable income, including the gain:

Short-term gains use the ordinary income brackets instead (10%, 12%, 22%, 24%, 32%, 35%, 37%).

How the long-term tax is calculated

Your taxable income fills the brackets first; then the gain stacks on top and is split across whichever 0/15/20% bands are left:

In the example above, the single filer's $80,000 income already passes the $48,350 zero-rate ceiling, so the entire $50,000 gain falls in the 15% band: $50,000 × 0.15 = $7,500. If part of your income sat below $48,350, that slice of the gain would be taxed at 0%.

The 3.8% Net Investment Income Tax (NIIT)

High earners owe an extra 3.8% NIIT on investment income. It applies to the lesser of your net investment income or the amount your modified AGI exceeds $200,000 (single or head of household) or $250,000 (married filing jointly). For example, a single filer with $250,000 of MAGI that includes a $50,000 gain pays 3.8% on the full $50,000 (because MAGI exceeds the threshold by more than the gain), adding $1,900 on top of the regular capital gains tax.

Ways to reduce the tax

• Hold over one year: turns ordinary-rate short-term gains into 0/15/20% long-term gains.
• Harvest losses: capital losses offset capital gains dollar-for-dollar, and up to $3,000 of ordinary income per year.
• Time the sale: realizing gains in a lower-income year can keep you in the 0% or 15% band.
• Use tax-advantaged accounts: gains inside a 401(k) or IRA aren't taxed until (or unless) you withdraw.

How to use this capital gains calculator

You only need a few numbers to get a realistic federal estimate. Work through the fields in order:

1. Gain amount: enter your profit - the sale price minus your cost basis (what you paid, plus commissions and qualifying improvements). Do not enter the full sale price.
2. Holding period: mark the gain as long-term if you held the asset more than one year, or short-term if you held it one year or less. This single switch usually changes the tax the most.
3. Filing status: choose single, married filing jointly, or head of household. The status sets which 0/15/20% breakpoints and which NIIT threshold apply.
4. Other taxable income: add your taxable income before the gain. The calculator stacks the gain on top of this to decide which long-term band it falls into.
5. State rate (optional): if you want to fold in state tax, type your state's rate; leave it blank for a federal-only estimate.

The result updates instantly: read the estimated federal tax, any 3.8% NIIT, the effective rate on the gain, and your net proceeds after tax.

Who this calculator is for

This tool is built for anyone who has sold - or is about to sell - an appreciated asset and wants a quick, accurate tax estimate. That includes:

• Investors selling stocks, ETFs, mutual funds, or bonds in a taxable brokerage account.
• Crypto holders realizing gains, since the IRS treats digital assets as property subject to capital gains rules.
• Home sellers with a gain above the primary-residence exclusion ($250,000 single / $500,000 married), or selling a second home or rental.
• Employees selling vested RSUs, ESPP shares, or exercised stock options after the holding clock has run.
• Year-end planners deciding whether to harvest losses or defer a sale into January to land in a lower bracket.

A second worked example: hitting the 0% band

Suppose you are a single filer with just $30,000 of taxable income and you sell stock for a $20,000 long-term gain. Your income sits $18,350 below the $48,350 zero-rate ceiling, so the first $18,350 of the gain is taxed at 0%. The remaining $1,650 spills into the 15% band, costing $1,650 × 0.15 = about $248 in federal tax. You keep nearly all of the gain. The lesson: a low-income year is a powerful window to realize long-term gains cheaply - sometimes completely tax-free at the federal level - which is why retirees and people between jobs often time sales for exactly those years.

Scenario comparison: same $50,000 gain, different situations

Using a $50,000 gain as the baseline, here is how a few common choices change the federal tax (illustrative, federal only):

• Held 6 months, $80,000 other income (single): short-term, taxed as ordinary income near your 22%-24% marginal rate - roughly $11,500.
• Held 18 months, $80,000 other income (single): long-term in the 15% band - $7,500, a saving of about $4,000 just from waiting past the one-year mark.
• Held 18 months, $30,000 other income (single): part of the gain lands in the 0% band, so the tax drops to roughly $3,200.
• Held 18 months, $250,000 MAGI (single): 20% top band plus the 3.8% NIIT can push the combined federal bill toward $11,900 on the same gain.

The takeaway: holding period, your other income, and the NIIT threshold often move the bill far more than people expect for an identical-sized gain.

Key terms explained

• Cost basis: what you originally paid for the asset, plus commissions, fees, and qualifying improvements. Gain = sale price − cost basis.
• Realized vs. unrealized gain: a gain is only taxed when you realize it by selling. Paper (unrealized) gains on assets you still hold are not taxed.
• Holding period: the clock starts the day after you buy and ends on the sale date. More than one year = long-term; one year or less = short-term.
• MAGI (modified adjusted gross income): the income figure used to test the 3.8% NIIT thresholds ($200,000 single/HoH, $250,000 MFJ).
• Wash sale: if you sell at a loss and buy a substantially identical security within 30 days, the IRS disallows the loss for that sale.
• Step-up in basis: inherited assets generally reset to their fair market value at the date of death, often erasing the prior gain for heirs.

What changes the result the most

If you adjust the inputs and watch the tax move, a few factors dominate:

• Holding period: the single biggest lever - short-term (ordinary rates up to 37%) versus long-term (0/15/20%) can roughly halve the bill.
• Your other income: it fills the brackets first, deciding whether the gain lands in the 0%, 15%, or 20% band.
• Gain size: a very large gain can push part of itself from the 15% band into the 20% band, or over the NIIT threshold.
• Filing status: married filing jointly has roughly double the breakpoints, so the same gain can be taxed lower.
• State rate: a high-tax state can add several percentage points; states with no income tax add nothing.

Limitations and assumptions

This calculator is a planning estimate, not a tax return. Keep these assumptions in mind:

• It estimates federal capital gains tax (plus NIIT) and adds state tax only if you enter a rate; it does not apply state-specific rules, brackets, or exemptions.
• It does not net capital losses or loss carryforwards against your gain - net those yourself before entering the figure.
• It excludes special regimes such as the qualified small business stock (QSBS) exclusion, collectibles (taxed up to 28%), Section 1250 depreciation recapture on real estate (up to 25%), and the AMT.
• It assumes the gain is fully taxable; it does not apply the home-sale exclusion or 1031 like-kind exchange deferral.
• Figures use 2025 thresholds (returns filed in 2026). Brackets are inflation-adjusted each year.

How it compares to related calculators

This page answers "how much tax will I owe on this gain?" If you have a different question, a sister tool fits better:

• To estimate tax on your wages and total income, use the Income Tax Calculator.
• To find your marginal bracket, use the Tax Bracket Calculator.
• To see the average rate across all your income, use the Effective Tax Rate Calculator.
• To estimate a refund or balance due, use the Tax Refund Calculator.
• To check take-home pay after withholding, use the Paycheck Calculator.