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Instructions

This page explains what each calculator does and how to interpret the results. Use the menu at the top to switch back to a calculator anytime.

📋 Quick Navigation

🚀 Getting Started 📊 Method 1: Total Risk % 💰 Method 2: Dollar Risk 📈 Method 3: Position % 🔍 Interpreting Results ⚠️ Disclaimer ℹ️ About ☕ Support

🚀 Getting Started: Pick Your Method

All three calculators answer the same question: "How many shares should I buy?"

The difference is HOW you want to define your risk:

  • 1 Total Risk %: "I risk a fixed % of my account per trade"
  • 2 Dollar Risk: "I risk a fixed dollar amount per trade"
  • 3 Position %: "I allocate a fixed % of my account to each position"
💡 Pro tip: Try all three with the same entry/stop prices to see how they differ!

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📊 Method 1: Total Account Risk %

When to Use This

Use this method if you prefer thinking about risk as a percentage of your total account. For example: "I'm willing to risk 1% of my $10,000 account ($100) on this trade."

How It Works

This calculator:

  1. Takes your account value and the risk percentage you choose
  2. Calculates how many dollars that represents as maximum risk
  3. Uses your entry and stop loss prices to determine how many shares you can buy
  4. Optionally limits your position size if you specify a max number of positions

Step-by-Step

  1. Account Value: Your total trading account balance
  2. Total Account Risk %: The percentage you're willing to risk (typically 0.5% - 2%)
  3. Entry Price: The price where you plan to buy
  4. Stop Loss: The price where you'll exit if the trade goes against you
  5. Max Positions (optional): If you want to limit how much of your account goes into any single trade
  6. Click Submit to calculate

What You'll Get

Max Shares: How many shares you can safely buy
Position Size: Total dollar amount invested
Risk per Share: How much you lose per share if stopped out
Dollars Risked: Total money at risk on this trade

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💰 Method 2: Dollar Amount Risk

When to Use This

Use this method if you think in terms of fixed dollar amounts. For example: "I want to risk $100 maximum on this trade, no matter what."

How It Works

This calculator:

  1. Takes the dollar amount you're willing to risk
  2. Looks at the gap between your entry and stop loss prices
  3. Calculates how many shares you can buy while staying within your dollar risk limit

Step-by-Step

  1. Dollar Risk: The maximum dollar amount you're willing to lose on this trade
  2. Entry Price: The price where you plan to buy
  3. Stop Loss: The price where you'll exit if the trade goes against you
  4. Account Value (optional): Your total account—helps see what percentage of your account this trade represents
  5. Click Submit to calculate

What You'll Get

Max Shares: How many shares you can safely buy
Position Size: Total dollar amount invested
Risk per Share: How much you lose per share if stopped out
Dollars Risked: Confirms your maximum risk amount
Position Size as % of Account: Shows what percentage of your account this trade uses

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📈 Method 3: Position % Allocation

When to Use This

Use this method if you want to allocate a percentage of your capital to each trade. For example: "I want to put 5% of my account into this position."

How It Works

This calculator:

  1. Takes the account value (or allocation amount) and percentage you specify
  2. Calculates how many dollars that percentage represents
  3. Uses your entry and stop loss to determine how many shares you can buy with that allocation
  4. Shows you how much risk you're taking per share

Step-by-Step

  1. Account Value / Allocation Amount: Your total account or the amount you want to allocate to this trade
  2. Position Risk %: The percentage of that amount to invest (use the quick preset buttons or adjust the slider)
  3. Entry Price: The price where you plan to buy
  4. Stop Loss: The price where you'll exit if the trade goes against you
  5. Click Submit to calculate

What You'll Get

Max Shares: How many shares you can safely buy
Position Size: Total dollar amount invested
Risk per Share: How much you lose per share if stopped out
Trade Risk: The actual percentage of your account at risk
Dollars Risked: Total money at risk on this trade

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🔍 Understanding Your Results

Max Shares

The maximum number of shares you should buy. This is your position size limit. Buy this many or fewer.

Position Size

The total dollar amount you'll invest if you buy the max shares at your entry price. For example: 100 shares × $50 entry = $5,000 position size.

Risk per Share

How much money you lose on each share if stopped out. Calculated as: Entry Price − Stop Loss = Risk per Share

Dollars Risked

Your maximum total loss if the trade hits your stop loss. This is what you specified in Method 1 & 2, or what results from your allocation in Method 3.

History

Every time you click Submit, your calculation is saved in the History section. This helps you review past trades and see your sizing decisions over time. Click Clear to reset the calculator without saving to history.

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Disclaimer

This calculator is for educational purposes only and does not constitute financial advice. Trading involves risk, and you should consult with a qualified financial professional before making any trading decisions. By using this calculator, you acknowledge that you assume all responsibility for your trades and the results thereof.

About

This calculator was developed and maintained for the r/swingtrading community by moderator Cheungster.

At r/swingtrading, the mission is evidence-based education and empowering traders to prioritize risk management.

View on GitHub: https://github.com/marcd35/position_sizing_calculator

Support

Domain and hosting costs are independently supported by friendly and generous folks like yourself. If you find this free tool useful, support is appreciated.

Buy me a coffee

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