Capital Gains Calculator

What is a capital gain or loss?

A capital gain is the profit you realise when you sell a capital asset — a stock, bond, piece of real estate, cryptocurrency, collectible or other investment — for more than your adjusted cost basis in that asset. A capital loss is the opposite: you sell for less than your basis.

Capital gains are taxed differently from wages. Long-term gains are taxed at preferential federal rates of 0%, 15% or 20%; short-term gains, on assets held one year or less, are taxed as ordinary income at rates from 10% to 37%. That difference is why the holding period matters: the same dollar gain can be taxed very differently a day apart.

Gains and losses are realised — and taxable — only when you sell or otherwise dispose of the asset; a gain on a position you still hold is not taxed. Capital losses offset capital gains, and a net capital loss offsets up to $3,000 of ordinary income a year ($1,500 married filing separately), with the rest carried forward (IRS Topic 409).

When is a gain long-term, and what are the 2026 rates?

A gain is long-term when you held the asset for more than one year. The holding period starts the day after you buy and includes the day you sell, so a sale on the first anniversary of the purchase is still short-term and the day after is long-term (IRS Publication 550). Bought 15 January 2025: long-term from 16 January 2026.

Count by the calendar, not by 365 days. Across a 29 February the anniversary is 366 days away: bought 1 February 2024, a sale on 1 February 2025 — 366 days later — is still short-term. Bought on 29 February 2024, the anniversary is 28 February 2025 and 1 March 2025 is the first long-term day. The calculator applies the anniversary rule and shows the first long-term date.

The 2026 long-term rates (IRS Rev. Proc. 2025-32 §4.03): 0% on taxable income up to $49,450 (single), $98,900 (married filing jointly) or $66,200 (head of household); 15% up to $545,500, $613,700 or $579,600; 20% above. Short-term gains are taxed with ordinary income at 10% to 37%.

The 3.8% Net Investment Income Tax can apply on top when modified adjusted gross income exceeds $200,000 (single) or $250,000 (married filing jointly), on the lesser of net investment income or the excess (IRS Topic 559) — a top long-term rate of 23.8%. This calculator classifies the gain and gives the rate context; the tax itself depends on your full income.

What counts in cost basis and adjusted basis?

Your cost basis is generally what you paid for an asset, including the purchase commission, brokerage fee or closing costs. Shares bought for $10,000 with a $9.95 commission have an adjusted basis of $10,009.95, not $10,000. Selling costs come off the proceeds instead. Both change the size of the gain.

Basis can change over time. For real estate, capital improvements — a new roof, an added bathroom — increase it, and depreciation you claimed reduces it (with recapture taxed at up to 25% on sale). For securities, return-of-capital distributions reduce it and splits change the per-share figure. Inherited assets generally take a basis equal to the value at the date of death (IRC §1014).

If you own several lots of the same security bought at different prices, the method — first-in, first-out, specific identification or average cost for fund shares — decides which basis is used. This calculator models one lot; for several, enter each lot separately from your broker's cost-basis records.

How are crypto and real estate gains treated?

The IRS treats cryptocurrency as property (Notice 2014-21), so a sale, a swap for another coin or spending it is a taxable disposal under the same short- and long-term holding rules and the same basis methods as securities. This calculator handles crypto exactly as it handles stocks: enter the total purchase cost and total sale proceeds in dollars.

Investment real estate follows the same capital-gains rules, with two additions this calculator does not model: depreciation recapture, taxed at up to 25% on the depreciation you claimed (IRC §1250), and instalment sales, where each payment carries part of the gain into the year it is received. For a rental property with prior depreciation, use Schedule D and Form 4797.

For a main home, up to $250,000 of gain ($500,000 married filing jointly) can be excluded if you owned and lived in it for at least two of the five years before the sale (IRS Publication 523). The calculator cannot verify occupancy, so it does not apply the exclusion; see worked example 2.

What does this capital gains calculator not calculate?

It computes the gain or loss and classifies the holding period; it does not compute the dollar tax owed. That needs your total taxable income, filing status, every other gain and loss for the year, and your deductions — the federal tax depends on where the gain stacks on top of your other income.

State tax is not modelled. Most states tax capital gains as ordinary income at their own rates; a few have no personal income tax, and some treat gains separately. Check your state revenue department's current rules.

Depreciation recapture, instalment sales, wash sales across accounts, the home-sale exclusion and the §1202 small-business stock exclusion are outside a general calculator. The wash-sale flag here is a single-lot warning. For filing, use your Form 1099-B and Schedule D, and a tax professional for property or large losses. This is an educational estimate, not tax advice.