Capital Gains Tax Calculator
Estimate US capital gains tax — short-term and long-term rates for 2025 including NIIT
Know your tax bill before you sell
Capital gains tax can take a significant bite out of your investment returns. Know the estimate before you decide when to sell.
2025 tax rates
Uses the current long-term capital gains brackets and ordinary income rates for 2025.
Short vs long term
Compare how much more you pay on a short-term gain versus holding one more day.
NIIT calculation
Includes the 3.8% Net Investment Income Tax for high-income investors.
Filing status
Adjusts brackets for both single filers and married filing jointly.
Effective rate
Shows the effective tax rate on your gain for easy comparison between scenarios.
100% private
All calculations run in your browser. No financial data is stored or transmitted.
When to use it
Selling stocks
Find out the tax cost of selling a stock position before you pull the trigger.
Selling property
Estimate the tax on a real estate sale, especially investment properties.
Timing decisions
See the cost of selling now vs. waiting for long-term rates to apply.
Tax planning
Model whether harvesting losses in the same year can offset gains.
Frequently Asked Questions
What are the 2025 long-term capital gains tax rates?
For 2025, long-term capital gains (assets held over one year) are taxed at 0%, 15%, or 20% depending on your taxable income. Single filers pay 0% up to $48,350, 15% up to $533,400, and 20% above that. Married filing jointly thresholds are $96,700 and $600,050. Additionally, high earners may owe the 3.8% Net Investment Income Tax (NIIT) on amounts above $200,000 (single) or $250,000 (MFJ).
What is the difference between short-term and long-term capital gains?
Short-term capital gains apply to assets held for one year or less and are taxed as ordinary income at your regular income tax rate (10–37% for 2025). Long-term capital gains apply to assets held for more than one year and are taxed at the preferential rates of 0%, 15%, or 20%. Holding an asset just one day past the one-year mark can significantly reduce your tax bill.
What is the Net Investment Income Tax (NIIT)?
NIIT is a 3.8% surtax on investment income for higher earners. It applies to the lesser of your net investment income (including capital gains) or the amount by which your modified adjusted gross income exceeds $200,000 (single) or $250,000 (married filing jointly). It applies on top of regular capital gains tax, potentially pushing your effective rate to 23.8% at the top.
Do I pay capital gains tax when I sell a house?
Not always. The primary home exclusion allows you to exclude up to $250,000 of capital gains ($500,000 if married filing jointly) if you have owned and lived in the home as your primary residence for at least 2 of the last 5 years. Gains above the exclusion are taxed at long-term capital gains rates (if held over a year). Investment properties do not qualify for this exclusion.
What are capital losses and how do they help?
A capital loss occurs when you sell an asset for less than you paid. Capital losses can offset capital gains dollar-for-dollar — if you have $10,000 in gains and $6,000 in losses, you only pay tax on $4,000. If your losses exceed gains, you can deduct up to $3,000 of net capital loss against ordinary income per year, and carry forward any remaining loss to future years indefinitely.
Understanding Capital Gains Tax
Capital gains tax is one of the most actionable taxes in personal finance — unlike income tax, you often choose when to trigger it by deciding when to sell an asset. Understanding how it works turns tax timing into a real tool for increasing your after-tax returns.
The holding period rule
The single most impactful factor in capital gains taxation is how long you hold an asset. Assets held for more than one year qualify for long-term rates of 0–20%, far below the 10–37% ordinary income rates that apply to short-term gains. Holding one day past the one-year mark is not always practical for timing reasons, but when circumstances allow, it can cut your tax rate in half on the same gain.
Tax-loss harvesting
Capital losses offset capital gains dollar for dollar before any tax is calculated. Selling losing positions in the same year as winning ones reduces your net gain and thus your tax. This strategy — tax-loss harvesting — is particularly useful at year-end, when investors review their portfolio and selectively realize losses to offset gains they have already taken. The key rule: do not repurchase the same or substantially identical security within 30 days (the wash-sale rule) or the loss is disallowed.
Step-up in basis at death
One of the most favorable features of US capital gains tax is the step-up in basis at death. When an appreciated asset is inherited, the heir's cost basis is reset to the asset's fair market value at the date of death, eliminating the capital gain that accrued during the original owner's lifetime. This makes holding appreciated assets until death potentially far more tax-efficient than gifting or selling them while alive — a key consideration in estate planning.