How to use the stock profit calculator
The calculator has three tools. Profit & return is the one most people need: it takes a trade you made, or plan to make, and shows the money result. Break-even price shows the price you need just to cover your costs. Target price works backwards from the profit you want.
- Choose the position. Long means you buy first and sell later, profiting when the price rises. Short means you sell borrowed shares first and buy them back later, profiting when the price falls.
- Enter the number of shares and the prices. Use the actual fill prices from your broker’s confirmation, not the price you saw on the chart, because they often differ by a few cents.
- Enter the commissions in dollars per trade. If your broker charges per share, multiply first: 500 shares at $0.005 a share is $2.50.
- Add the days held if you want the annualized return. Leave it empty to skip it.
The results update as you type. The chart under the results shows the net profit at every exit price around your trade, with the break-even point marked, so you can see at a glance how much room the trade has.
The formulas
For a long position, the profit is the change in value of the shares minus the costs of trading them:
Return = Net profit ÷ (Buy price × Shares + Buy fee)
Break-even price = Buy price + (Buy fee + Sell fee) ÷ Shares
Annualized return = (1 + Return)365 ÷ days − 1For a short position the price difference is reversed: (Sale price − Buy-back price) × Shares, and the break-even price is below the entry price instead of above it.
The return is measured against the money you actually put in, including the commission on the purchase. That is the honest denominator: it is the cash that left your account.
A worked example
You buy 100 shares shares at $50 and pay a $5 commission. Later you sell them at $62.50 and pay another $5.
The shares rose by 25.00%, which is worth $1,250.00 on 100 shares shares. After $10.00 in fees, the net profit is $1,240.00.
You invested $5,005.00 including the purchase fee, so the return is +24.78%. Because you held the shares for 365 days, the annualized return is the same figure.
If the same gain had taken only 60 days, the annualized return would be +284.40%. That number is not a forecast: it only says that if you could repeat this trade six times a year, this is what it would compound to. It is useful for comparing trades of different lengths, and dangerous if you treat it as an expected yearly return.
A short sale works in reverse. If you sold 100 shares shares short at $50 and bought them back at $40, the net profit would be $990.00.
Why fees matter more on small positions
Commissions are charged per trade, not as a percentage, so their effect depends on the size of the position. With $10 of fees in total:
| Position | Break-even price | Rise needed to break even |
|---|---|---|
| 10 shares at $50 | $51.00 | 2.00% |
| 100 shares at $50 | $50.10 | 0.20% |
| 1,000 shares at $50 | $50.01 | 0.02% |
On a $500 position the same fees need the stock to rise 2.00% before you make a cent; on a $50,000 position they are almost invisible. That is why small accounts trading frequently lose a surprising share of their gains to costs, and why the break-even tool is worth checking before a short-term trade.
Profit, return and annualized return: which number to use
Each of the three numbers answers a different question.
- Net profit answers “how much money did I make?” It is what matters for your bank balance and for tax.
- Return answers “how well did the money work?” It lets you compare a $500 trade with a $50,000 one.
- Annualized return answers “how fast did it work?” It lets you compare a two-week trade with a two-year holding.
A trade with a large profit can still have a poor return if it tied up a lot of capital, and a high annualized return on a very short trade often says more about luck than skill. Looking at all three together gives the clearest picture.
Long and short positions
When you buy shares, the most you can lose is what you paid, and the potential gain has no ceiling. A short position is the mirror image: the gain is capped at the entry price (the share price cannot fall below zero), while the potential loss has no ceiling, because there is no limit to how high a price can rise.
Short sales also carry costs this calculator does not include. Your broker charges a fee to borrow the shares, which can be high for heavily shorted stocks, and if the company pays a dividend while you are short, you owe that dividend to the lender.
What this calculator does not include
The results cover the price change and the commissions you enter. Several things can change the real outcome:
- Dividends received while you held the shares add to the return. Our total return calculator includes them.
- Taxes reduce the profit you keep, and the rate depends on how long you held the shares.
- Margin interest applies if you bought with borrowed money.
- Currency conversion matters if you trade shares in a currency other than your account currency.
- Bid-ask spread and slippage are already in your fill prices if you use the prices from your trade confirmation, but not if you use a quoted last price.
For tax records, use the cost basis method your broker reports, especially if you bought the same stock several times at different prices.