Stock Profit Calculator

Fees apply on both sides

Profit is not simply the sale price minus the purchase price. Commission on the buy, commission on the sale, and in some markets a transaction tax or stamp duty all come out of the position. Break-even is therefore above your entry price, not at it — a point that matters most on small positions, where a flat commission can be a significant percentage of the trade.

Percentage return needs the right denominator

Return is profit divided by the total amount invested including the buy-side costs, not divided by the share price. Getting this wrong overstates performance slightly on every trade and materially on small ones. Comparing two trades of different sizes requires the percentage; comparing your result against an index requires it too.

Gains and losses are not symmetrical

A 50 percent loss requires a 100 percent gain to recover, because the gain is measured from the reduced balance. A 20 percent loss needs 25 percent. This asymmetry is why avoiding large drawdowns matters more than capturing large gains, and it is consistently underweighted because both numbers are quoted in the same units.

Annualise before comparing

A 15 percent gain over three months and a 15 percent gain over three years are different outcomes entirely. Annualising by taking the nth root of the growth multiple makes them comparable. Without it, short profitable trades look identical to long mediocre ones.

Dividends belong in total return

Price appreciation alone understates the return on any dividend-paying holding. Total return adds dividends received, and over long periods reinvested dividends have historically accounted for a large share of equity returns. A price-only calculation on a high-yield holding can show a loss where the total return was positive.

Tax comes off the realised gain

Nothing is owed until you sell, and the rate usually depends on how long the position was held. A trade that looks profitable before tax can be substantially less so after, particularly at short holding periods where preferential long-term rates do not apply.