Free calculator
Capital gains tax calculator (U.S. federal)
Estimate U.S. federal tax on a capital gain from cost, optional improvements, and sale proceeds. Choose short-term vs long-term (or let purchase and sale dates decide). Long-term uses 0% / 15% / 20% rates with stacking on other taxable income you enter. Short-term uses your marginal ordinary percent—this is not a full Form 1040 engine. State, NIIT, recapture, wash sales, and 1031 are out of scope—see FAQs.
When to use this calculator
Quick federal-only gain and tax illustrations before you open tax software or a model—same spirit as a scratch block in Sheets or Excel.
- Compare short-term vs long-term treatment when you already know basis and proceeds.
- See how other taxable income shifts the 0% / 15% / 20% slices on a long-term gain (stacking).
- Copy a simple gain line into a workbook row before you add state, NIIT, or lot detail elsewhere.
- Jump to the ROI calculator for pre-tax return on the same two cash totals—this page adds a federal tax layer only.
We start from adjusted basis = cost + capital improvements you type, then gain = sale proceeds − adjusted basis. Losses show zero federal tax here (carryforward rules are not modeled).
Short-term vs long-term
Short-term applies to property held one year or less in auto date mode (we use the same 365.25‑day year conversion as the ROI tool’s date span). Long-term applies when held more than one year.
Short-term tax line
We multiply the gain by your marginal ordinary rate (percent) that you enter. That avoids shipping a full ordinary bracket engine while still giving a transparent illustration.
Long-term tax (stacking)
We stack the long-term gain on top of other taxable income (before this gain) and walk it through 0%, 15%, then 20% slices using IRS-style 2025 breakpoints for the filing status you pick.
What we do not model
State taxes, the 3.8% NIIT, AMT, depreciation recapture, wash sales, crypto lot methods, foreign tax, estimated payments, and like-kind (1031) deferral. For pre-tax return on two totals, use the ROI tool.
German Abgeltung and French plus-value immobilière tools answer different statutes—this page stays on U.S. federal rules in v1 while localized copy explains the boundary. For pre-tax return on invested vs returned cash, open the ROI calculator. For growth with contributions over time, use the compound interest calculator.
Google Sheets & Excel (gain line)
English US/UK patterns below. A sheet still needs Form 8949 discipline for real filings—we show one gain cell you can align with this page’s definition.
=B2-A2Add improvements in a helper cell (for example =A2+C2 for basis in A2 and improvements in C2) if you keep them separate.
Frequently asked questions
What tax does this calculator actually estimate?
U.S. federal tax on one capital gain number: short-term as gain × your marginal %, long-term with 0% / 15% / 20% slices stacked on other taxable income you enter. It is not a full Form 1040 or 8949 replacement.
How do short-term and long-term differ here?
Short-term uses your supplied ordinary marginal percent on the whole gain. Long-term walks the gain through the LTCG bands after your other income—see methodology for the stacking story.
What counts as basis and improvements?
Basis is generally what you paid to acquire the asset (plus certain costs to buy). Improvements are capitalized costs that increase basis in real life—we only add the numbers you type. Verify asset-class rules with IRS publications or a professional.
Does this include state capital gains or California surcharges?
No. Only the federal lines described on this page. State rules vary widely; use state-specific guidance or software when that matters.
What about the 3.8% Net Investment Income Tax (NIIT)?
We do not add NIIT in v1. If you are above statutory thresholds, real liability can be higher—treat this page as a partial federal illustration.
Can I model a 1031 exchange deferral?
No. Like-kind exchanges have their own forms and timelines. This page assumes a taxable sale unless you manually set proceeds to reflect a different story in your own model.
How do I match the gain in Google Sheets or Excel?
Use =sale−(basis+improvements) with your own cell references—see the copy card. Tax still needs your broader workbook or tax product; we do not emit 8949 rows.
Why might this differ from TurboTax, H&R Block, or my CPA?
Products apply state, AMT, NIIT, carryforwards, lot selection, and ordinary bracket detail. This page keeps a small transparent slice so you can sanity-check a federal gain story.
Can I use this for crypto?
You can type any proceeds and basis in the same unit, but we do not model FIFO/LIFO, wash sales, or airdrops. Treat the answer as illustration only.
Is this tax or legal advice?
No. It is a free educational calculator—not a filing position and not a substitute for qualified professionals when money or compliance is on the line.