Position size calculator (fixed-risk)
Position sizing converts a planned trade idea into a precise number of shares using your account size, the percent of equity you are willing to risk, and the distance between your entry and stop. The formula is: shares = (account × risk%) / |entry − stop|. This calculator implements the classic fixed-fractional rule used by professional discretionary and systematic traders alike.
How to use
- Enter account equity
The total dollar value of the trading account.
- Pick risk percent
Most pros risk 0.25%–1% per trade. Use 1% as a sane default.
- Enter entry and stop
The two price levels that define your maximum acceptable loss.
- Read the result
Drogo returns share count, dollar risk and total notional.
Frequently asked questions
- What is a safe risk-per-trade percent?
- Most professional discretionary traders risk 0.25%–1% of equity per trade. Survival math: at 2% risk, a 10-trade losing streak — common in any system with 50% accuracy — draws you down ~18%.
- Should I include commissions and slippage?
- Yes for live trading. Subtract estimated round-trip commissions and 1–3 ticks of slippage from your effective stop distance before sizing.
- How does this differ from Kelly?
- Fixed-fractional risks the same percent every trade regardless of edge. Kelly varies size with edge — see the Kelly criterion calculator.
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