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Instant Calculation
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Position sizing — deciding how many shares to actually buy — is one of the most important risk management decisions in trading, yet it's often reduced to guesswork instead of a consistent, risk-based calculation.
This calculator finds exactly how many shares to buy so that a stop-loss hit only risks a fixed percentage of your account, with a full step-by-step solution.
How it works
Enter your total account size, the percentage of your account you're willing to risk on this trade, and your planned entry and stop-loss prices. The calculator finds the dollar amount at risk, divides it by the per-share risk (the distance between entry and stop-loss), and rounds down to a whole number of shares.
- Enter account size ($).
- Enter risk per trade (%).
- Enter entry price.
- Enter stop-loss price.
- Click Calculate to see your results.
Examples
Risking 1% of a $10,000 account
With a $10,000 account, 1% risk per trade, an entry price of $50, and a stop-loss at $48, the position size is 50 shares — risking exactly $100 if the stop-loss is hit.
Who should use it
- Determining how many shares to buy for a specific risk tolerance before entering a trade.
- Comparing position sizes across trades with different stop-loss distances.
Industry applications
- Trading and risk management
- Financial market education
Advantages
- Enforces consistent, disciplined risk management across every trade.
- Includes a complete, formula-based step-by-step solution.
Limitations
- Doesn't account for trading commissions, fees, or slippage on execution.
Common mistakes to avoid
- Sizing a position based on a "gut feeling" dollar amount rather than a consistent percentage-of-account risk calculation.
- Forgetting to update the position size when the stop-loss distance changes, which changes the correct share count.
Best practices
- Decide on your stop-loss level before calculating position size, not after — the stop-loss distance is what determines a properly risk-sized position.
Tips
- A wider stop-loss (further from entry) always produces a smaller position size for the same dollar risk — position sizing and stop-loss placement are directly linked, not independent decisions.