Stock profit and loss is the difference between the total revenue from selling shares and the total cost of buying them, including any commission fees. Knowing exactly how much you make or lose on each trade is essential for evaluating your strategy and making informed decisions about future investments.

The formula is straightforward: Net Profit = (Sell Price x Shares - Sell Commission) - (Buy Price x Shares + Buy Commission). Return on investment, or ROI, expresses that profit as a percentage of your total cost. A positive ROI means you made money on the trade; a negative ROI means you lost money.

For example, if you buy 100 shares at $150 and sell them at $185 with no commissions, your total cost is $15,000 and your total revenue is $18,500. That gives you a net profit of $3,500 and an ROI of 23.33%. The break-even price is the minimum sell price needed to cover your cost, which in this case is exactly $150 per share when there are no commission fees.