Position Size Calculator

It works out how many shares you can buy so that, if the stock falls to your stop-loss, you lose only the percentage of your account you chose to risk.

Account size

The total value of your trading account.

Risk per trade

The percent of your account you are willing to lose if the stop is hit.

Entry price

The price you plan to buy at.

Stop-loss price

The price where you would sell to cut the loss.

Shares to buy is the dollar risk divided by the loss per share. Dollar risk is how much you would lose if the stop is hit exactly. Position value shows how much of your account the trade uses.

$25,000 account, 1% risk = $250. Entry $100, stop $95, so you risk $5 per share. $250 ÷ $5 = 50 shares, a $5,000 position (20% of the account).

• Confusing risk per trade with position size. Risking 1% does not mean buying 1% of your account.
• Assuming the stop guarantees your exit price. Prices can gap past it.
• Placing the stop based on how many shares you want rather than on the chart or plan.