HenryCalc

Capital gains tax calculator

Estimate short- and long-term federal capital gains tax plus the 3.8% NIIT on your gain.

Federal capital gains tax$15,000
Net investment income tax (3.8%)$3,800
Total federal tax (18.8%)$18,800
Net after federal tax$81,200

How capital gains are taxed

How long you held an asset changes everything. A short-term gain (held one year or less) is taxed as ordinary income at your marginal rate, which can be as high as 37%. A long-term gain (held more than a year) gets the preferential 0%, 15% or 20% rates. For 2026, the 0% rate applies up to $49,450 of taxable income for single filers, 15% applies in the middle band, and 20% begins at $545,501.

What this calculator estimates

Enter your gain, whether it is short or long-term, your other taxable income, and your filing status. The tool stacks the gain on top of your income to find the right rate, adds the 3.8% net investment income tax if you are over the threshold, and shows your total federal tax and net.

Why the stacking matters

Long-term rates depend on your total income, not the gain alone. A large gain can push part of itself from the 15% band into the 20% band, and high earners almost always owe the extra 3.8% NIIT on top. State tax is separate - most states tax gains as ordinary income - so add your state rate to get the full picture.

Frequently asked questions

What is the difference between short and long-term capital gains?
Assets held one year or less are short-term and taxed as ordinary income at your marginal rate. Assets held longer than a year are long-term and taxed at the preferential 0%, 15% or 20% rates based on your taxable income.
What is the 3.8% NIIT?
The net investment income tax adds 3.8% on investment income for single filers with modified adjusted gross income over $200,000 and joint filers over $250,000. These thresholds are not adjusted for inflation.
Does this include state tax?
No. This estimates federal capital gains tax and NIIT only. Most states tax capital gains as ordinary income, so add your state rate separately.

Last reviewed January 2026. This calculator provides general educational estimates based on the inputs you enter and simplified assumptions. It is not financial, tax, legal or investment advice, and figures may differ from your actual liability. Verify with a licensed CPA or financial advisor before acting.