Capital Gains Tax Calculator
Finance & InvestmentCalculate your US federal capital gains tax using 2025 IRS rates. Covers short and long-term gains for single, married, and head-of-household filers.
Capital Gain
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Rates shown are 2025 federal rates. State capital gains taxes are additional. NIIT (3.8%) may apply if your income exceeds $200K (single) or $250K (married).
What is a Capital Gains Tax?
A Capital Gains Tax Calculator computes your estimated federal tax liability when you sell an appreciated asset — stocks, ETFs, mutual funds, real estate, cryptocurrency, or any other capital asset. It applies 2025 IRS tax rates to show you exactly how much of your sale proceeds will go to federal taxes and how much you keep as net proceeds.
Capital gains taxes in the US have two tracks based entirely on how long you held the asset. Short-term gains — on assets held one year or less — are taxed at your ordinary marginal income rate, which can reach 37%. Long-term gains — on assets held more than one year — are taxed at preferential rates of 0%, 15%, or 20%, depending on your taxable income. The difference between these two rates can be enormous: a $50,000 gain taxed at 37% costs $18,500; that same gain taxed at 15% costs $7,500 — a $11,000 swing based purely on whether you held the asset one extra day past the one-year mark.
For high-income taxpayers, the 3.8% Net Investment Income Tax (NIIT) applies on top of the standard capital gains rates, raising the effective maximum rate to 23.8% (long-term) or 40.8% (short-term, including ordinary income rates). The NIIT threshold — $200,000 for single filers, $250,000 for married filing jointly — has not been adjusted for inflation since the tax was introduced in 2013.
Understanding your capital gains tax before you sell helps you make better decisions: whether to wait until an asset crosses the one-year holding threshold, whether to harvest offsetting losses in the same tax year, or whether to use tax-advantaged accounts for higher-growth positions. For long-term tax-free growth, the Roth vs Traditional IRA Calculator models how keeping gains inside a Roth IRA eliminates capital gains taxes entirely.
How to use this Capital Gains Tax calculator
Enter your Purchase Price — the original cost basis of the asset. For stocks, this is your purchase price per share times number of shares. For real estate, include purchase price plus closing costs and capital improvements. For crypto, include the price plus exchange fees paid.
Enter your Sale Price — the proceeds from the sale. For stocks and crypto, use the proceeds after any exchange or brokerage fees. For real estate, use the gross sale price before closing costs (closing costs reduce your gain separately).
Select Holding Period — "Short-term" for assets held one year or less, "Long-term" for assets held more than one year. This is the most consequential single input — it determines whether you pay ordinary or preferential rates.
Select your Filing Status — choose Single, Married Filing Jointly, or Head of Household. This determines which income thresholds apply to each capital gains rate bracket.
Enter your Ordinary Income — your estimated taxable income from non-capital-gains sources for the current year. This positions your capital gain on the tax bracket stack. If uncertain, use your taxable income from last year's Form 1040 (line 15) as a starting estimate.
Review the four outputs — confirm the Capital Gain is what you expected. Check the Tax Rate to see if you are in the NIIT zone. Use Tax Owed to make your sell / hold decision. Note Net Proceeds for reinvestment planning.
Formula & Methodology
Capital Gain: Capital Gain = Sale Price − Purchase Price Short-term capital gains tax (ordinary income rates, 2025, single): Tax owed = Marginal tax on (Ordinary Income + Capital Gain) − Marginal tax on Ordinary Income Where marginal tax is computed using 2025 ordinary income brackets: 10% / 12% / 22% / 24% / 32% / 35% / 37%. Long-term capital gains rate (2025): Taxable income = Ordinary Income + Capital Gain | Filing Status | 0% threshold | 15% threshold | 20% threshold | |---|---|---|---| | Single | ≤ $48,350 | ≤ $533,400 | > $533,400 | | Married / Joint | ≤ $96,700 | ≤ $600,050 | > $600,050 | | Head of Household | ≤ $64,750 | ≤ $566,700 | > $566,700 | The rate applies to the capital gain portion above the ordinary income. If $30,000 of ordinary income straddles the 0% and 15% thresholds, the gain is split accordingly. NIIT (Net Investment Income Tax): NIIT applies at 3.8% on the lesser of: - Net investment income (including capital gains), or - MAGI − $200,000 (single) / $250,000 (married filing jointly) Net Proceeds: Net Proceeds = Sale Price − Tax Owed Worked example: Single filer, ordinary income $60,000, purchased stock for $20,000 three years ago, sold for $50,000 (long-term gain of $30,000). Taxable income = $60,000 + $30,000 = $90,000 Long-term rate at $90,000 (single): above $48,350 → 15% bracket Tax owed (LTCG) = $30,000 × 15% = $4,500 NIIT check: $90,000 < $200,000 → no NIIT Net Proceeds = $50,000 − $4,500 = $45,500 Now compare with selling after only 10 months (short-term): Ordinary income bracket at $90,000: 22% marginal rate Short-term tax = $30,000 × 22% = $6,600 Net Proceeds = $50,000 − $6,600 = $43,400 Waiting the full year saves $2,100 on this transaction. Key assumptions: The calculator computes federal capital gains tax only — it does not include state income taxes (which can add 0–13.3% depending on your state), the primary residence exclusion, depreciation recapture on real estate, or wash sale rule adjustments. Always verify with a tax professional before making large asset sales.
Frequently Asked Questions