Stock Position Size & Risk Calculator
Optimize your stock trading strategy: calculate exact position sizes and simulate risk with Monte Carlo analysis.
Stock Essentials
Advanced Sizing
Shares to Buy
Risk Analysis
Visual Metrics
Stock Portfolio Drawdown
Simulated impact of consecutive losses on your equity.Monte Carlo Stock Simulation
Projected equity paths based on win rate and risk parameters.The Mathematics of Stock Trading Survival
Successful stock trading is a game of probabilities. To protect your capital, you must understand how position sizing and risk management prevent the risk of ruin.
Consecutive Loss Probability
Statistical likelihood of loss streaks over 1,000 stock trades. Even with a 50% win rate, a streak of 9-11 losses is mathematically certain.
| Win Rate | Max Loss Streak |
|---|---|
| 30% | 20 to 22 |
| 40% | 14 to 16 |
| 50% | 9 to 11 |
| 60% | 7 to 9 |
| 70% | 4 to 5 |
Capital Recovery Asymmetry
The deeper your drawdown, the harder it is to recover. Protecting capital is more vital than seeking returns.
| Capital Loss | Recovery Gain Needed |
|---|---|
| -10% | +11.1% |
| -25% | +33.3% |
| -50% | +100% |
| -75% | +300% |
| -90% | +900% |
Comprehensive Guide & Feature Breakdown
Stock Essentials: The Foundation
Account Equity: Your total account value (cash + the market value of all open positions). This is the base used to calculate your dollar risk.
Available Cash: The liquid capital you currently have to open new trades. The calculator ensures your position size never exceeds your buying power.
Risk Per Trade (%): The percentage of your total equity you are willing to lose if the stop loss is hit. Professionals often keep this between 0.5% and 2%.
Stock Entry Price: The price at which you plan to buy the stock.
Stop Loss Price: The "exit" price if the trade goes against you. This gap between entry and stop loss defines your risk per share.
Advanced Sizing Parameters
Fees Type & Value: Account for real trading costs (Fixed or Percentage). This adjusts shares so your total risk (drop + fees) stays within your limit.
Max Exposure (%): A safety cap that prevents allocating too much of your total account to one single stock ticker.
Risk/Reward Ratio (R/R): The target profit relative to risk. A ratio of 3 means you aim to gain $3 for every $1 at risk.
Win Rate: Your success rate, used to fuel the Monte Carlo and Drawdown simulations.
Understanding Results & Metrics
Shares to Buy: The exact quantity to purchase to respect your risk settings.
Effective Risk: The true percentage of your account at risk, including all transaction fees.
Capital Exposure: The percentage of your total equity tied up in this position.
Drawdown Simulation: Visualizes the impact of a "losing streak." If the curve drops too sharply, your risk per trade is too high for your psychology or account.
Monte Carlo Simulation: Projects 20 random paths for your equity over 100 trades. It helps you understand the variance and potential outcomes of your strategy over time.