Stock Profit Calculator
"I bought at $50 and sold at $65" sounds like a $15/share win — until commissions take their cut off both ends. Get your true net profit, the honest return %, and the exact sell price that breaks even.
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Where the money goes
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The math most people skip
A trade has four cash flows, not two. You pay the share cost plus the buy commission going in, and you receive the sale value minus the sell commission coming out. Net profit is what survives both ends — and the breakeven sell price sits above your buy price by exactly the round-trip commissions divided by shares.
Return % = net profit ÷ (buy × shares + buy commission)
Breakeven sell = (buy × shares + buy commission + sell commission) ÷ shares
Worked example
Buy 100 at $50 ($5,000 + $10 commission = $5,010 in), sell at $65 ($6,500 − $10 = $6,490 out). Net profit = $1,480, a 29.54% return on the $5,010 actually invested. Breakeven sell = $5,020 ÷ 100 = $50.20 — the stock must rise 0.4% before you make a cent.
Why commissions hit small trades hardest
A $20 round trip is a rounding error on a $50,000 position (0.04%) but a 4% headwind on a $500 one. That's why frequent small trades with flat-fee brokers are a slow bleed: the math demands a gain just to stand still. Zero-commission brokers removed this drag for US stocks — but options, OTC, and most non-US brokers still charge, so the breakeven line above still earns its keep.