Position Size Calculator
Calculate how many shares to buy based on your account size, risk tolerance, and stop-loss level. Enter your trade setup to see the optimal position size, dollar risk, and portfolio exposure. Based on the percentage risk model used by traders to manage risk on every trade.
Educational purposes only.
This calculator provides estimates for educational purposes. Actual trading involves additional risks including slippage, gaps, and market volatility that may cause losses to exceed the calculated risk. This is not financial advice.
Educational purposes only. These calculators illustrate concepts and do not constitute investment advice. Read our disclaimer
StockCram is not a broker-dealer, investment adviser, or financial institution. All content is for educational and informational purposes only and should not be construed as personalized investment advice. Consult a qualified financial professional before making investment decisions. Past performance does not guarantee future results.How It Works
Enter your account size
Your total trading account balance — the basis for calculating risk.
Set your risk percentage
The maximum percentage of your account you are willing to lose on this trade (commonly 1-2%).
Enter entry and stop loss prices
Your planned entry price and the stop-loss price where you would exit to limit losses.
Review your position size
See how many shares to buy, dollar risk, position value, and portfolio exposure percentage.
Frequently Asked Questions
Position sizing is the process of determining how many shares (or units) to buy or sell on a trade. It is based on your account size, how much you are willing to risk on a single trade, and the distance between your entry price and stop-loss price. Proper position sizing helps manage risk so that no single trade can significantly damage your portfolio.
The 1% rule means risking no more than 1% of your total account on any single trade. The 2% rule is a slightly more aggressive version. For example, with a $50,000 account and a 2% risk rule, the maximum you would risk on one trade is $1,000. These guidelines help limit drawdowns and preserve capital over many trades.
Position size is calculated by dividing your dollar risk (account size multiplied by risk percentage) by the risk per share (the difference between entry price and stop-loss price). For example, if your dollar risk is $1,000 and the risk per share is $10, you would buy 100 shares. The result is typically rounded down to whole shares.
A stop loss defines the price at which you exit a trade to limit losses. Without a stop loss, you cannot calculate the risk per share, which means you cannot determine a proper position size. The stop loss is what makes position sizing mathematical rather than guesswork — it turns an undefined risk into a measurable one.
This depends on your trading style and risk tolerance. Many traders keep individual positions between 5-10% of their portfolio. Concentrated positions (above 20-25%) increase portfolio volatility. The position size calculator shows your portfolio exposure percentage so you can evaluate whether a trade is appropriately sized for your account.