Phase 4 · General Utility
Capital Gains Tax Calculator
The same profit, taxed two very different ways. Set your basis, sale price and holding period to see the tax you owe now — and the cash that crossing the one-year line keeps in your pocket.
Under the hood
The math, fully exposed
We split the gain by holding period, then stack it on your other income:
Capital gain = sale proceeds − cost basis
Short-term (≤12 mo) = taxed as ordinary income, stacked on your other income
Long-term (>12 mo) = 0% / 15% / 20%, by where the gain lands above your income
Saved = short-term tax − long-term tax
- The one-year line is a cliff, not a slope: at 12 months and one day the same gain can drop from your ordinary rate to 15% — often the largest single tax lever an investor controls.
- Gains stack on income: a long-term gain piled on a high salary can spill from the 15% band into 20%, so your other income changes the rate on the gain itself.
- Federal core only: state tax, the 3.8% NIIT and loss offsets sit on top of this — the real bill can be higher.
Your directives
What to do next, based on your numbers
Adjust the sliders to generate tailored recommendations.
Answers
Frequently asked questions
What is the difference between short- and long-term capital gains?
It is all about the holding period. Sell an asset you have held one year or less and the gain is a short-term gain, taxed at your ordinary income rate — up to 37%. Hold it more than a year and it becomes a long-term gain, taxed at the preferential 0%, 15% or 20% rate. For most investors that is the difference between a ~22–24% bill and a 15% one on the same profit.
How are the 0%, 15% and 20% long-term rates decided?
Long-term gains stack on top of your other taxable income. The portion landing in the lowest band is taxed at 0%, the middle band at 15%, and only very high incomes reach 20%. In 2025 a single filer pays 0% on long-term gains while total taxable income stays under about $48,350, then 15% up to about $533,400. This tool stacks your gain on your other income to find the blended rate.
Does this include state tax or the NIIT?
No. This models federal capital-gains tax only. It excludes state income tax (most states tax gains as ordinary income), the 3.8% Net Investment Income Tax that applies above roughly $200k–$250k, and the effect of capital losses you can use to offset gains. The real bill can be higher — treat this as the federal core of the calculation and confirm specifics with a tax professional.
Should I always wait for long-term treatment?
Usually the tax savings are large, but not always decisive. If the position is risky and you have a big gain, locking it in can beat holding for a tax break that a price drop would erase. The tax tail should not wag the investment dog — but when the fundamentals are neutral, crossing the one-year line is often the single cheapest way to keep more of your profit.