Stock profit calculator
Stock profit calculator: enter shares, buy price, sell price and both commissions to get the cost basis, net proceeds, gross profit, tax and net profit, plus return on investment, annualised return and the break-even sell price.
Runs in your browserEvery computation happens in your browser — your data never leaves this device.
Trade details
Amounts are computed in integer cents, share counts support up to 4 decimals, and commissions are entered as absolute amounts.
Profit and loss
1001,005.001,195.00190.000.00190.002.0018.91%18.91%10.10What this tool does
- Check what a closed trade actually earned once both commissions are included.
- Work out the break-even sell price before buying, so you know the price that gets you back to zero.
- Add a tax rate on gains to see the net profit and return you really keep.
- Compare annualised returns across holding periods to judge whether short-term trading beats holding.
Example
Input
100 shares, buy price 10, sell price 12, 5 commission on each side, tax rate 0%
Output
Cost basis 1,005.00, net proceeds 1,195.00, gross profit 190.00, net profit 190.00, profit per share 2.00, return on investment 18.91%, break-even sell price 10.10
The break-even price is above the buy price because both commissions have to be earned back: 10.10 × 100 − 5 = 1,005.00, exactly the cost basis.
Frequently asked questions
Why does my broker show a different return?
Most brokers fold commissions, stamp duty and transfer fees straight into cost or proceeds. Here the cost basis is “buy amount + buy commission” and net proceeds are “sell amount − sell commission”. If you also pay stamp duty or transfer fees, add them to the matching commission and the numbers line up.
Do I pay tax on a loss?
No — the tax here only applies to a positive gross profit; when the gross profit is zero or negative the tax is zero. How losses are treated in reality depends on your local tax code, and losses are often carried forward, so confirm with a tax professional.
How is the annualised return computed?
By compounding: annualised = (1 + return)^(365 ÷ days held) − 1. Hold for 365 days and it equals the period return; double your money in 30 days and the annualised figure is huge, because it simply extrapolates the same rate for a full year.
Does it handle fractional shares or fund units?
Yes. You can enter up to 4 decimals (0.5 shares, for instance) and the tool scales shares by 10000 and works in integers, so 0.5 shares at 10 never produces a floating point rounding error.
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