What is the Stock Return Calculator?
The Stock Return Calculator is a tool that accurately calculates your actual net profit and return rate by factoring in trading commissions and securities transaction tax. Instead of just looking at the difference between buy and sell prices, you can see the real amount you take home.
It provides default values for Korea's 2026 securities transaction tax (0.18%) and online trading commission (0.015%), which you can freely adjust. It also automatically calculates the break-even selling price so you know the minimum price to sell at to avoid losses.
Key Features
Real-time P&L Calculation
Enter buy price, sell price, and quantity to instantly calculate net profit and return rate including all fees and taxes.
Commission & Tax Included
Reflects both buy/sell commissions and securities transaction tax for accurate real-world profit calculation.
Auto Break-even Calculation
Automatically calculates the minimum sell price (break-even point) considering all commissions and taxes.
Comma-formatted Numbers
Large amounts are automatically formatted with thousand separators for easy reading, and results can be copied.
How to Use
- Enter Buy Info — Input the buy price per share and the number of shares.
- Enter Sell Price — Input the actual or expected sell price per share.
- Check Fees & Tax — Review defaults (commission 0.015%, tax 0.18%) and adjust if needed.
- View Results — Check net profit, return rate, and break-even sell price.
Use Cases
Pre-sell Profit Simulation
Calculate how much actual profit you would make if you sold your shares at a specific price.
Target Return Reverse Calculation
Find out the minimum sell price needed to achieve your desired profit target.
Broker Fee Comparison
Compare actual profits across different brokers by entering their respective commission rates.
Break-even Point Check
Identify the minimum sell price after fees and taxes to prevent losses.
Frequently Asked Questions
What is securities transaction tax?
Securities transaction tax is a tax imposed when selling stocks. As of 2026 in Korea, both KOSPI and KOSDAQ have a 0.18% tax rate. No tax is charged on purchases — only on the sell amount.
How is commission calculated?
Commission is charged on both buy and sell transactions. It is calculated by multiplying the trade amount (price x quantity) by the commission rate. Rates vary from 0.003% to 0.5% depending on the broker and trading method (online/offline/mobile). The default 0.015% represents the online trading average.
What is the break-even point (BEP)?
The break-even point is the price at which you neither profit nor lose, after accounting for all fees and taxes. You must sell above this price to generate actual profit. It factors in buy commission, sell commission, and securities transaction tax.
What is the 2026 transaction tax rate?
As of 2026, both KOSPI and KOSDAQ have a securities transaction tax rate of 0.18%. This has been gradually reduced from 0.20% in 2023. Note that the special rural development tax is separate. This calculator only reflects the securities transaction tax.
Is my data stored?
No. This calculator processes all calculations in your browser. Your trading information is never sent to any server. All data is cleared when you close the page.
Privacy Notice
This stock return calculator processes all calculations in your browser. Your buy/sell information is never sent to any server, and no investment data is stored.
Calculating Stock Returns Properly — Including Costs and Taxes
The valuation gain shown on your trading screen is only a pre-tax, pre-cost number. What actually lands in your account is left after subtracting buy/sell commissions, securities transaction tax, dividend tax, and in some cases capital gains tax. Because Korea's securities transaction tax rose starting in 2026, the bite that costs take out of your return is now larger than before — especially for active, short-term traders. This article shows the gap between headline and realized returns in numbers and clears up the cost and tax items people often miss.
Simple Return vs. Realized Return
Simple (headline) return is (sell price − buy price) ÷ buy price. Realized return, by contrast, reflects every cost incurred at purchase plus every cost and tax deducted at sale, then measures net profit against the capital you actually committed. The gap widens the more often you trade and the shorter you hold. That's why a '+1%' on the quote board can turn into break-even or a loss once you actually sell.
- Buying costs: brokerage commission (typically 0.01–0.015%, lower with online discounts). No transaction tax applies when buying.
- Selling costs: brokerage commission + securities transaction tax (charged only on sales).
- While holding: dividends are subject to 15.4% dividend tax, withheld at source.
Korean Stock Taxes and Transaction Rates for 2026
The key point about securities transaction tax is that it applies to the full sale amount regardless of whether you made a profit. You pay it even when you sell at a loss. The 2026 rates by market are as follows.
| Category | 2026 Rate | Notes |
|---|
| KOSPI (transaction + rural tax) | 0.20% (0.05% tax + 0.15% rural special tax) | On sale |
| KOSDAQ | 0.20% | No rural special tax |
| Dividend tax | 15.4% (14% income + 1.4% local) | Withheld; comprehensive taxation if annual financial income exceeds 20M KRW |
| Large-shareholder capital gains (≤300M) | 22% | Local tax included |
| Large-shareholder capital gains (>300M) | 27.5% | Local tax included |
Ordinary small shareholders pay no capital gains tax on profits from domestic listed stocks. However, large shareholders (holding 5 billion KRW or more per stock, or a stake of 1% on KOSPI / 2% on KOSDAQ / 4% on KONEX) are subject to capital gains tax. Large-shareholder status is judged by holdings as of the last day of the prior December, so trimming positions at year-end to stay under the threshold is a common strategy.
Worked Example — Short-Term KOSPI Trade
Assume you buy at 1,000,000 KRW and sell at 1,050,000 KRW (0.015% commission both ways, 0.20% KOSPI sell transaction tax).
- Buy commission: 1,000,000 × 0.015% = 150 KRW, total cost basis 1,000,150 KRW
- Sell commission: 1,050,000 × 0.015% = 157 KRW
- Transaction tax: 1,050,000 × 0.20% = 2,100 KRW
- Net proceeds: 1,050,000 − 157 − 2,100 = 1,047,743 KRW
- Net profit: 1,047,743 − 1,000,150 = 47,593 KRW → realized return about 4.76%
The headline return was +5.0%, but after costs and taxes the realized return was 4.76% — 0.24 percentage points vanished. If you turn over the same stock 10 times a year, costs alone can erase more than 2 percentage points annually. The shorter your trade, the more your 'break-even price' always sits above your buy price.
Overseas Stocks and Common Average-Price Mistakes
Unlike domestic stocks, profits from overseas stocks are subject to 22% capital gains tax (local tax included) even for small shareholders, with a 2.5 million KRW annual basic deduction, self-reported and paid the following May. Gains and losses can be netted within the same year, so selling a losing position before year-end can lower your taxable base. Exchange rates are applied at each settlement date for the buy and the sell, so even a dollar gain can shrink or turn into a loss in won terms if the rate falls.
- Average-price illusion: even if averaging down lowers your average price, the rebound needed to recover is larger than the loss. A −20% loss needs +25% to break even.
- Splitting the deduction: the 2.5M KRW overseas deduction renews each year, so splitting sales across year-end and the new year lets you use it twice.
- Ignoring FX gains/losses: your true profit is measured in won. Don't judge by the dollar-denominated return alone.