Stock Profit and Loss Calculator

How to Use This Stock Profit Calculator

Enter your buy price per share, sell price per share, and the number of shares traded. Add any commissions paid on the buy and sell side, choose whether they're flat fees or percentages, and optionally enter your capital gains tax rate. Hit Calculate to see your net profit or loss, return on investment, and a full cost breakdown.

Why This Matters

Knowing your actual profit after fees and taxes is very different from knowing your gross gain. Many investors see a 10% move in a stock and assume they're up 10%—but broker commissions, exchange fees, and capital gains tax can quietly erode returns, especially on smaller positions or high-frequency trading.

Consider this: you buy 100 shares of a stock at $50 ($5,000 invested), it rises to $58, and you sell. That's an $800 gross gain—16% ROI. But if you're paying $10 each way in commissions and owe 20% capital gains tax, your net profit drops to $620, and your real ROI falls to about 12.4%. On a $500 position, fees could wipe out an entire month of gains.

This calculator is useful for active traders tracking individual positions, long-term investors evaluating whether to sell, tax planning before year-end, and anyone comparing a stock's performance against other investments like ETFs or bonds.

How It's Calculated

The formulas used in this calculator:

• Total Buy Cost = (Buy Price × Shares) + Buy Commission
• Total Sell Revenue = (Sell Price × Shares) − Sell Commission
• Gross Profit/Loss = Sell Revenue − Buy Cost
• Tax Amount = Gross Profit × (Tax Rate ÷ 100) (only if profit > 0)
• Net Profit/Loss = Gross Profit − Tax Amount
• ROI (%) = (Net Profit ÷ Total Buy Cost) × 100
• Break-Even Price = (Total Buy Cost + Sell Commission) ÷ Shares

When you select percentage fees, the commission is calculated as: Buy Fee % × (Buy Price × Shares), and similarly for the sell side.

Tips & Common Mistakes

• Don't forget both sides of the trade. Many people only account for the buy commission, but broker fees are charged on entry and exit.
• Use the correct tax rate. Short-term gains (held under 1 year in the US) are taxed as ordinary income (up to 37%), while long-term gains are taxed at 0%, 15%, or 20%.
• Losses have tax value too. A realized loss can offset capital gains elsewhere — this calculator shows your total loss so you can factor it into tax-loss harvesting.
• Check your break-even price. This is the price the stock must reach just to cover all your costs. It's often higher than people expect.
• Compare ROI vs. time held. A 5% gain sounds great, but if it took 3 years, that's less than 2% annualized—potentially less than a savings account.

Frequently Asked Questions

What is ROI in stock trading?

ROI (Return on Investment) measures how much profit you made relative to your initial investment, expressed as a percentage. A 20% ROI means you earned $20 for every $100 invested. It helps you compare the performance of different trades or investments on equal footing, regardless of how much capital was deployed.

Does this calculator work for short selling?

Yes — for a short sale, enter your sell price as the "Buy Price" (where you opened the position) and your buy-to-cover price as the "Sell Price." The calculator will correctly show profit if the stock fell and a loss if it rose. Just reverse the labels mentally.

How do I handle fractional shares?

You can enter decimal values for shares (e.g., 2.5 shares). The calculator handles fractional quantities correctly, making it useful for brokers like Robinhood or Fidelity that offer fractional share investing in stocks and ETFs.

What's the difference between gross and net profit?

Gross profit is your gain before deducting fees and taxes — just the difference between what you sold for and what you paid. Net profit is what you actually keep after commissions and any applicable capital gains tax. Net profit is the number that matters for your real-world financial outcome.

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