Stock profit in 3 steps
- Purchase costbuy price × shares, plus the buy commission
- Sale proceedssell price × shares, minus the sell commission and any transaction tax on the sale
- Profit and taxprofit before income tax = sale proceeds − purchase cost; capital gains tax = profit × your rate, only when the profit is positive
Net return = net profit ÷ (buy amount + buy commission) × 100
How to calculate stock profit
The simple way to judge a trade is to compare the sell price with the buy price. That number, the gross return, ignores what the trade actually cost you. This stock profit calculator starts from the same numbers and then subtracts every cost you enter, so you see the amount that really ends up in your account.
- Purchase cost = buy price × shares, plus the buy commission.
- Sale proceeds = sell price × shares, minus the sell commission and any transaction tax on the sale.
- Profit before income tax = sale proceeds − purchase cost.
- Capital gains tax = profit × your rate, only when the profit is positive.
- Net return = net profit ÷ (buy amount + buy commission) × 100.
The break-even sell price is the price at which the trade exactly covers its commissions and transaction tax: (buy amount + buy commission) ÷ (shares × (1 − sell commission % − transaction tax %)). Capital gains tax does not change it, because no tax is due when there is no gain.
Worked example
| Item | Calculation | Result |
|---|---|---|
| Purchase | 20 × 150.00 | 3,000.00 |
| Sale | 20 × 180.00 | 3,600.00 |
| Profit, zero commission | 3,600.00 − 3,000.00 | 600.00 (20.00%) |
| Capital gains tax at 15% | 600.00 × 15% | 90.00 |
| Net profit after tax | 600.00 − 90.00 | 510.00 (17.00%) |
| Same trade with 0.1% commission each way | 600.00 − 3.00 − 3.60 | 593.40 (19.76%) |
A 0.1% commission looks tiny, yet it took about a quarter of a percentage point off the return. On frequent short-term trades those small costs add up, while for a long-term holding they matter much less than the tax rate.
Tips for getting an accurate number
- Check your broker’s fee schedule. Commission-free trading is now common for stocks and ETFs at many brokers, but options, foreign shares, mutual funds and phone trades can still carry fees.
- Watch currency conversion. If you buy shares listed in another currency, the exchange spread on the way in and out works like an extra commission. You can add it to the commission percentage.
- Know your holding period. In many countries the capital gains rate drops after you hold for a set period, often a year. Selling a few days later can change your after-tax result more than the price does.
- Losses can offset gains. Many tax systems let you subtract realized losses from gains in the same year. This calculator looks at one trade, so check your full-year picture before estimating tax.
Reading a negative result
If the sell price is below the buy price, or costs are larger than the price gain, the net profit shows as a loss. No capital gains tax is applied to a loss, but commissions and transaction taxes still count. In many tax systems a realized loss can be used to reduce taxable gains elsewhere, which is why the after-tax cost of a loss can be smaller than it looks here.
Cautions
Tax rules differ widely between countries and change over time, so the rates in this page are examples only. The calculator assumes one purchase and one sale at fixed prices. It does not include dividends, withholding tax, margin interest, or account fees, and it does not give tax advice. For a position built over several purchases, work out your average cost first with the stock average calculator and use that as the buy price.