Stock Profit Calculator

What this calculator tells you

The profit or loss on a share holding is the difference between the money you received on selling and the money you paid on buying, after the costs of both transactions. This calculator shows the net gain or loss in money and as a percentage of the amount invested.

Fees matter more than many people expect. A small charge on each trade can turn a modest gain into a smaller one, or a small loss into a larger one, so the calculator includes them in the result.

How the result is worked out

The cost of the purchase is the number of shares multiplied by the buying price, plus any buying fees. The proceeds of the sale are the number of shares multiplied by the selling price, minus any selling fees. The profit is the proceeds minus the cost. The percentage is the profit divided by the cost, multiplied by 100.

A worked example

Suppose you buy 100 shares at 20 and sell them at 26, with fees of 10 on each trade. The cost is 2,000 plus 10, which is 2,010. The proceeds are 2,600 minus 10, which is 2,590. The profit is 580, and the return is 580 divided by 2,010, which is about 28.9%. Without fees the gain would have been 600, or 30%, so the fees reduced the result by about 20.

Realised and unrealised gains

A profit becomes real only when the shares are sold. Until then, the gain is unrealised and can disappear if the price falls. This calculator works on a completed trade, so it is best used to review a sale that has happened or to model a sale you are planning. Tax is usually due on realised gains, and the rules depend on your country and the type of account.

Limits of the calculation

The calculator uses the prices and fees you enter. It does not include taxes, currency conversion, dividends received during the holding period, or the bid-offer spread, which is the difference between buying and selling prices. Dividends can add to the total return, and a currency movement can increase or reduce the gain for holdings priced in another currency.

Taking a small loss or a small gain on a single trade tells you little about the quality of a decision. Review many trades over time before drawing conclusions about your results.

Keeping a trade record

Record the date, price, number of shares and all fees for each buy and sell. These details are needed for accurate tax reporting in many countries, and they let you review your decisions honestly over time. Patterns in past trades, such as cutting winners early or holding losers too long, are easier to spot with a written record.

Using the result

Use the result to check the outcome of a trade after costs, to plan a sale, and to keep a record for tax purposes. Keep the purchase price, the sale price, and all fees and dates, because these are usually needed to calculate the gain correctly for tax.

Reviewing trades against a plan

Compare each completed trade with the plan that was written before it was entered. Note whether the stop and target were hit, whether the plan was followed and what the result was after costs. Over time, this review shows whether the gains came from a sound process or from luck, and it highlights the habits that need changing.