Capital Gains Tax Calculator
Estimate tax on short-term vs long-term capital gains for the 2026 tax year.
Held >1 year — preferential rates
Held ≤1 year — taxed as ordinary income
Total Capital Gains Tax
$4,500
Effective Rate: 15.0%
Long-Term Tax
$4,500
15.0%
Short-Term Tax
$0
0%
NIIT (3.8%)
$0
above $200K MAGI
| Category | Amount | Tax | Rate |
|---|---|---|---|
| Long-Term Capital Gains | $30,000 | $4,500 | 15.0% |
| Short-Term Capital Gains | $0 | $0 | — |
| Total Tax on Gains | $30,000 | $4,500 | 15.0% |
How This Is Calculated
This calculator estimates your capital gains tax by applying the appropriate tax rates based on how long you held the asset and your total taxable income.
Long-term capital gains (assets held >1 year) use preferential rates: 0% on gains that keep total taxable income below $49,450 (single) / $98,900 (married jointly), 15% up to $545,500 / $613,700, and 20% above those thresholds (2026 brackets).
Short-term capital gains (assets held ≤1 year) are taxed as ordinary income using the standard federal tax brackets (10%–37%). The calculator computes the incremental tax by comparing your tax with and without the short-term gains.
Net Investment Income Tax (NIIT): An additional 3.8% applies to investment income (including capital gains) when your modified adjusted gross income exceeds $200,000 (single) or $250,000 (married filing jointly). This calculator factors in NIIT automatically.
Based on IRS 2026 tax brackets. LTCG: 0%/15%/20% preferential rates. NIIT: 3.8% on investment income above $200K (single) / $250K (MFJ). State taxes not included in this estimate.
How to Read Your Results
What the numbers mean and how to use them
The Capital Gains Calculator shows how much tax you owe when you sell an investment. The single most important factor is not the gain amount — it is how long you held the asset. Holding an asset just one day past the one-year mark can cut your tax rate from 37% (short-term) to 0-20% (long-term).
Short-term vs long-term rate
If you held the asset ≤1 year, the gain is taxed as ordinary income (10-37%). If you held it >1 year, you pay preferential LTCG rates of 0%, 15%, or 20%. On a $50,000 gain for a $120,000-income earner, that is the difference between ~$11,000 (short-term) and ~$7,500 (long-term).
What to do: If you are close to the one-year mark, check the purchase date — waiting even a few weeks can save thousands.
Your LTCG bracket (0% / 15% / 20%)
Your long-term rate depends on total taxable income, not the gain alone. For 2026, a single filer earning under $49,450 pays 0% on long-term gains. Between $49,450 and $545,500 pays 15%. Above that pays 20%.
What to do: If your income is near a bracket boundary, consider spreading large gains across two tax years to stay in the lower bracket.
NIIT surtax (3.8%)
If your modified AGI exceeds $200,000 (single) or $250,000 (married), the calculator adds a 3.8% Net Investment Income Tax on top of your LTCG rate. At the 15% bracket, your effective rate becomes 18.8%.
What to do: High-income earners should budget for NIIT — it is often overlooked and can add thousands to a tax bill.
Net proceeds
This is what you actually keep after federal capital gains tax. On a $50,000 long-term gain at the 15% bracket, you keep $42,500 (before NIIT and state tax).
What to do: Use this number — not the gross gain — when deciding whether to sell. Many investors overestimate their after-tax proceeds.
When You'll Actually Use This
Selling employee stock options (RSUs)
Your RSUs vest and you sell immediately — that gain is always short-term (taxed as ordinary income). But if you hold vested shares over a year before selling, the appreciation qualifies for the 15-20% long-term rate. Use the calculator with your actual cost basis (vest-date FMV) to see the tax difference.
Tax-loss harvesting before year-end
If you have $20,000 in gains this year and $8,000 in unrealized losses in another position, selling the loser offsets $8,000 of the gains. Run both scenarios through the calculator to quantify the savings before December 31.
Retirement income planning
A retiree with $40,000 in Social Security + pension income can realize up to ~$9,450 in long-term gains at the 0% federal rate. Use this calculator to model how much you can harvest tax-free each year.
Frequently Asked Questions
What is the difference between short-term and long-term capital gains?
How does the Net Investment Income Tax (NIIT) work?
What are the 2026 long-term capital gains tax brackets?
How can I reduce capital gains taxes?
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Estimates only. Actual capital gains tax depends on your full tax situation. State taxes not included. Consult a tax professional.