Stock Profit and Loss Calculator

A trade's profit is the price difference multiplied by the share count, less what it cost to trade. On the tool's defaults, 100 shares bought at 12 and sold at 15 with 20 of commissions gives (15 − 12) × 100 − 20, or 280, which is 22.95% of the 1,220 cost basis. Commissions are a fixed amount against a variable gain, so their share of the outcome falls as trade size rises.

A worked example

With the defaults: buy price of 12, sell price of 15, shares of 100, total commissions of 20. The tool returns 280.00.

Here's a second scenario: you buy 500 shares at a price of 45, sell them at 52, and pay 125 in total commissions (entry and exit combined). The calculation runs as follows:

• Gross profit = (52 − 45) × 500 = 3,500
• Net profit = 3,500 − 125 = 3,375
• Cost basis = 45 × 500 + 125 = 22,625
• Percentage return = (3,375 ÷ 22,625) × 100 = 14.92%

In this case, commissions represent about 0.55% of the cost basis, leaving the overall return relatively unscathed. The same 125 in costs on a smaller trade, by contrast, would consume a much larger slice of profit.

What moves the number most

The two prices are the strongest levers, and they pull against each other. Raising each input by 1% of its own value moves the result 5.36% for the sell price, -4.29% for the buy price, 1.07% for the share count and -0.07% for commissions.

Two identities sit behind those figures. The sell and buy levers sum to the share lever, since the sell side contributes the sale proceeds and the buy side the outlay, and their difference is the gross gain. The share and commission levers sum to exactly 1, because the gross gain less commissions is the result itself. Both hold at every input vector, not only at these defaults.

The break-even sell price follows from the same arithmetic: the buy price plus commissions divided by shares, which is 12.20 on the defaults. Below that the trade loses money even where the share price rose.

Common scenarios where this matters

• Short-term trading: When hold periods are brief, commissions and bid-ask spreads form a larger percentage of total return, making this calculation more sensitive to cost.
• Position sizing: Traders evaluating whether to buy 100 shares or 1,000 shares can model how trade size affects the final dollar and percentage outcome.
• Entry and exit planning: Comparing two different exit prices or two different purchase prices illustrates the minimum gain needed to break even after costs.
• Broker selection: Swapping one commission figure for another shows the impact of brokerage fee structures on net returns.

What this does and does not capture

The calculator does compute the net profit or loss after subtracting all commissions from the gross gain. It expresses that outcome both in absolute currency terms and as a percentage return on your initial outlay.

The calculator does not account for taxes on gains, dividend income received during the holding period, changes in share price between purchase and sale that occur in real time (volatility), or the opportunity cost of capital tied up in the position. It treats the trade as a single transaction with a fixed entry and exit price, not a series of partial fills or adjustments.

Educational illustration

This result is for educational illustration only and models one scenario under simplified assumptions. Actual trading outcomes depend on market conditions, order execution, timing, and factors outside the scope of this tool.