How is the gain on a home sale calculated?

Gain = amount realized − adjusted cost basis. Amount realized is the sale price minus selling expenses (agent commission, closing costs). Adjusted cost basis is your purchase price plus the cost of capital improvements. The §121 exclusion ($250,000 single / $500,000 married) is then subtracted from the gain. (Source: IRS Publication 523.)

What tax rate applies to the taxable part of a home-sale gain?

If you owned the home more than a year, gain above the §121 exclusion is a long-term capital gain taxed at 0%, 15%, or 20% depending on your 2025 taxable income, plus a possible 3.8% Net Investment Income Tax for higher earners. (Source: IRS Topic No. 409; IRC §1411.)

Does this calculate state capital gains tax?

No. This estimate is federal only. Most states tax capital gains as ordinary income and rates vary widely; a few (such as Florida, Texas, and Washington for ordinary gains) have no state income tax. Check your state's rules separately. (Source: IRS Topic No. 409, federal scope.)

Is my data sent anywhere when I use this calculator?

No. All calculations run entirely in your browser using JavaScript. No sale price, basis, income, or other inputs are ever transmitted to any server.

Home Sale Capital Gains Tax Calculator 2025 — §121 Exclusion

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Home Sale Capital Gains Tax Calculator (2025)

This 2025 home sale capital gains calculator works out your gain (sale price − selling costs − cost basis), applies the §121 exclusion ($250,000 single / $500,000 married), and estimates the federal long-term capital-gains tax (0/15/20%) plus 3.8% NIIT on any taxable gain.

Enter your sale below to see the gain, how much the §121 exclusion covers, the taxable gain, and an estimate of the federal capital-gains tax and 3.8% NIIT. Everything runs in your browser — no data is transmitted.

Important: This is a federal estimate only. It does not compute state capital-gains tax, and it does not model depreciation recapture (unrecaptured §1250 gain, taxed up to 25%) if the home was ever a rental. Source: IRS Topic No. 701 & Publication 523 (§121 exclusion); IRS Topic No. 409 & Rev. Proc. 2024-40 (2025 long-term capital-gains thresholds); IRC §1411 (NIIT); figures for the 2025 tax year, data as of 2024-10-22. Rates and rules change; this is not tax or legal advice.