Position Size Calculator

Enter your account size, how much you’re willing to risk, your entry and your stop. The calculator gives you the exact number of shares to buy, so one bad trade never costs more than you planned.

The position size formula

Position size = (Account × Risk %) ÷ (Entry − Stop)

Example: you have a $10,000 account and risk 1% per trade. That’s $100. You buy at $50 with a stop at $48, so you risk $2 per share. $100 ÷ $2 = 50 shares, a $2,500 position.

Notice what decided the size: your stop, not how confident you feel. That’s the point.

Why position sizing matters more than your entry

Most new traders spend all their time on entries and none on size. Then one oversized loss wipes out a week of good trades. Fixed-risk sizing keeps every loss the same size, so your results come from your process, not from one lucky or unlucky trade.

Want the full breakdown of the four sizing methods pro traders use? Read our guide: Position Sizing: 4 Strategies to Protect & Grow Your Account.

FAQ

How do I calculate position size?

Take the dollar amount you are willing to lose (account size × risk %) and divide it by the distance between your entry and your stop. That gives you the number of shares.

What percent of my account should I risk per trade?

Most disciplined traders risk between 0.5% and 2% of their account on a single trade. Lower risk means a losing streak can’t knock you out.

Why does a tighter stop give me a bigger position?

Your dollar risk stays the same. A smaller gap between entry and stop means each share risks less, so you can hold more shares for the same total risk.

Does position size change my win rate?

No. Sizing controls how much you lose when you’re wrong. Your setup and your process decide how often you’re right.