Stock Return Calculator

The Stock Return Calculator is a comprehensive tool for computing the net profit and return rate on stock trades conducted on Korean exchanges (KOSPI and KOSDAQ). Unlike simple buy-minus-sell calculations, this calculator accurately accounts for all real-world transaction costs including brokerage commissions, the securities transaction tax, and market-specific tax rates. Understanding your true net return after all costs is essential for evaluating whether a trade was genuinely profitable and by how much. Many novice investors focus only on the share price difference and are surprised when their actual brokerage account balance shows a smaller gain than expected. This calculator eliminates that surprise by providing a transparent breakdown of every cost component. The tool also integrates with real-time stock data, allowing you to search for Korean stocks by name or code and auto-fill current market prices. This makes it convenient to quickly estimate potential returns on trades you are considering, or to calculate the exact profit on trades you have already completed. Whether you are a day trader making frequent transactions or a long-term investor evaluating your portfolio performance, this calculator gives you the precise numbers you need.

Step 1: Search for a stock using the search bar at the top. You can enter a company name (e.g., Samsung Electronics) or a stock code (e.g., 005930). Selecting a stock from the search results will auto-fill the current market price, saving you time. Step 2: Enter the buy price per share. This is the price at which you purchased (or plan to purchase) each share. If you bought at multiple prices, use the average purchase price. Step 3: Enter the sell price per share. This is the price at which you sold (or plan to sell). For hypothetical scenarios, enter your target sell price. Step 4: Enter the quantity of shares traded. This should be the total number of shares in the transaction. Step 5: Verify the fee rate. The default is 0.015%, which is the typical online/HTS brokerage rate. Adjust this if your broker charges a different rate. Note that phone or branch orders typically incur higher fees (0.1-0.5%). Step 6: Review the detailed results. The calculator displays gross profit, securities transaction tax, total brokerage fees, net profit, and the net return rate as a percentage. The breakdown section shows exactly how each component was calculated. Tip: Compare different sell price scenarios to find your break-even point — the minimum sell price needed to cover all transaction costs.

The calculation follows this precise sequence: 1. Buy Total = Buy Price × Quantity 2. Sell Total = Sell Price × Quantity 3. Gross Profit = Sell Total - Buy Total 4. Securities Transaction Tax = Sell Total × Tax Rate - KOSPI: 0% (abolished from 2025) - KOSDAQ: 0.18% (as of 2025) - K-OTC: 0.18% 5. Brokerage Fee = (Buy Total + Sell Total) × Fee Rate - Typical online/HTS rate: 0.015% - The fee applies to BOTH buy and sell sides 6. Net Profit = Gross Profit - Transaction Tax - Total Fees 7. Return Rate = (Net Profit / Buy Total) × 100 Worked Example: - Buy: 65,000 KRW × 100 shares = 6,500,000 KRW - Sell: 72,000 KRW × 100 shares = 7,200,000 KRW - Gross Profit: 700,000 KRW - Transaction Tax (KOSDAQ 0.18%): 7,200,000 × 0.0018 = 12,960 KRW - Brokerage Fees: (6,500,000 + 7,200,000) × 0.00015 = 2,055 KRW - Net Profit: 700,000 - 12,960 - 2,055 = 684,985 KRW - Return Rate: 684,985 / 6,500,000 × 100 = 10.54% Note: For KOSPI stocks, the transaction tax would be 0 KRW, yielding a higher net profit of 697,945 KRW (10.74% return). This difference illustrates why the market listing matters for your actual returns.

Understand the fee structure of your specific broker. While 0.015% is the standard online rate at most Korean securities firms, some brokers offer promotional zero-fee periods for new accounts or specific products like ETFs. Conversely, if you place orders by phone or at a branch, fees can jump to 0.1-0.5% — a massive difference on large trades. The abolition of KOSPI transaction tax from 2025 is a significant benefit for KOSPI-listed stock traders. However, KOSDAQ stocks still carry a 0.18% transaction tax on the sell side. This means that for short-term trades with thin margins, KOSPI stocks have a structural cost advantage. Remember that this calculator covers trading profit (capital gains from buying low and selling high) only. It does not include dividend income. For a complete picture of your investment return, combine this calculator with the Dividend Yield Calculator to account for both price appreciation and dividend payments. For frequent traders, transaction costs can significantly erode returns. If you make 100 round-trip trades per year with 0.015% fees on each side, that is an effective annual cost of 3% of your traded capital — a substantial drag on performance. Consider whether each trade truly has enough expected return to justify the costs. Tax considerations beyond transaction tax: If you are classified as a major shareholder (owning more than 1% of listed shares or with holdings exceeding certain thresholds), capital gains tax applies at rates of 20-25%. For most retail investors, domestic stock capital gains are not taxed (except for the transaction tax), but this may change with future tax reforms. Always calculate your break-even sell price before entering a trade. Your break-even is the minimum sell price needed to cover all costs. For a KOSDAQ stock bought at 10,000 KRW with 0.015% fees, your break-even is approximately 10,023 KRW — a 0.23% move just to avoid a loss.