Stock Profit Calculator

Most retail traders eyeball the share price difference and call it a day, which is exactly why the brokerage statement at year-end never matches what they thought they made. The right number is sale proceeds minus cost basis, where cost basis includes the buy commission and proceeds means sell price minus the sell commission — and on a taxable account you then subtract federal capital gains tax (state too if your state taxes investment income). The calculator runs all four steps so the gap between the headline gain and the after-tax number is visible before you place the trade. The reason this matters is that a 30% headline return on a short-term hold can land closer to 18% after a 22% federal bracket plus a typical state — and short-term gains are taxed at ordinary income rates, not the gentler 0/15/20% long-term brackets.

The line is one year and one day, and the tax difference is large enough that planning around it has built entire wealth-management strategies. Sell a stock you held for 365 days or fewer and the gain hits your federal tax return at the same rate as your wages — 10/12/22/24/32/35/37% depending on your bracket. Hold the same stock one day longer and the gain shifts to long-term capital gains rates: 0%, 15%, or 20% based on taxable income and filing status. For a single filer with $80,000 of taxable income in 2026, that flip moves the rate from 22% (ordinary) to 15% (LTCG) — a 7-point swing, which on a $10,000 gain is $700 left in your account instead of the IRS's. The calculator's holding-period toggle reflects this directly so you can see what waiting another month is actually worth.

Most retail investors look at long-term capital gains and assume the brackets work like ordinary tax brackets where the bigger your income, the bigger your bite — and they do not. A married couple sitting at $90,000 of taxable income in 2026 can sell stock for a $5,000 long-term gain and pay $0 federal tax on it, because the gain stacks onto income and only the slice crossing $98,900 starts getting taxed at 15%. The 2026 numbers (per IRS Rev Proc 2025-32 via the Tax Foundation): single filers hit the 15% LTCG bracket at $49,450 and the 20% bracket at $545,500; married filing jointly the breakpoints sit at $98,900 and $613,700; head of household at $66,200 and $579,600. Inflation pushed every threshold up roughly 2.7% from 2025 but the rate structure itself is unchanged. The 0% bracket is the part most retail investors leave on the table because they never run their actual taxable income against the threshold before realizing.

Cost basis is the price you paid for the shares plus the buy commission, full stop — but the way most retail brokers report it on the 1099-B is where the confusion starts. Robinhood and Fidelity both default to FIFO (first-in-first-out), which means selling 100 shares from a position you built across multiple purchases assigns the cost basis from your earliest buys. Specific identification — telling the broker exactly which lot to sell — almost always produces a better tax outcome but requires you to flag it before the sale settles. For employer stock from RSUs or ESPPs the cost basis includes the income already taxed at vest, which trips up enough people that the IRS warns about double-taxation in the Form 8949 instructions. The calculator assumes a single buy lot at the price you enter; for multi-lot positions, run it once per lot or pull the broker's realized gain/loss report.

Most traders chasing a loss harvest at year-end forget that the IRS has a 30-day fence around the trade — and that is where the wash-sale rule turns a tax-loss strategy into a tax bill that shows up the year after. Capital losses normally offset capital gains dollar-for-dollar, with any leftover loss reducing ordinary income by up to $3,000 per year. But sell at a loss and buy the same security or a "substantially identical" one within 30 days before or after the sale, and the loss is disallowed under IRS Publication 550. The disallowed amount rolls into the basis of the replacement shares — not gone forever, just deferred until those shares are sold. Apple to Microsoft is fine; Apple to Apple in any 60-day window is not. The calculator shows the negative gain when sale price drops below basis but does not apply tax to losses, and the wash-sale check is the trader's job.

The break-even math is straightforward and the calculator makes it visible: if your short-term tax rate is 22% and long-term rate is 15%, holding for the long-term qualification keeps an extra 7% of the gain. On a $10,000 gain that is $700 — but the question is whether the stock is worth holding for the additional weeks or months independent of taxes. The honest answer for most retail positions is that tax-tail-wagging-the-investment-dog is how people end up holding losers all the way down trying to qualify for LTCG. The calculator shows both scenarios side by side when you flip the holding-period toggle, so the comparison is concrete. The other consideration the toggle does not capture: if you have offsetting capital losses elsewhere in the portfolio, short-term gains can be wiped out by short-term losses with no rate penalty.