Position Size Calculator
for Swing Trading
Calculate exactly how many shares to buy based on your account size, risk tolerance, and stop loss. Built by swing traders, for swing traders.
Enter trade parameters to calculate position size
Required fields:
- Entry Price
- Stop Loss Price
- Account Value
- Risk Percentage
Why Position Sizing Matters
Position sizing is the difference between surviving and thriving as a swing trader. Even with a 60% win rate, poor position sizing can destroy your account.
A single oversized losing trade can wipe out weeks of profits. But proper position sizing—risking just 1-2% per trade—means you can survive 50+ consecutive losses before blowing up your account. That's the staying power that separates professional traders from amateurs.
How to Use This Calculator
Enter Your Account Size
Input your total trading account balance. This is the base for calculating how much you can risk.
Set Your Risk Per Trade
Choose what percentage of your account you're willing to risk. Most professionals use 1-2%.
Define Entry and Stop Loss
Enter your planned entry price and stop loss price. The difference determines your risk per share.
Get Your Position Size
The calculator shows exactly how many shares to buy while staying within your risk limit.
Position Sizing Methods Explained
Risk a fixed percentage of your account on each trade. The position size adjusts based on your stop loss distance.
Position Size = (Account × Risk%) / (Entry - Stop)Invest the same dollar amount in every trade regardless of risk parameters.
Position Size = Fixed Amount / Entry PriceAllocate a fixed percentage of capital to each position (e.g., 10% per trade).
Position Size = (Account × Position%) / EntryAdjust position size based on the stock's Average True Range for consistent risk across different volatility levels.
Position Size = (Account × Risk%) / (ATR × Multiplier)The 1-2% Risk Rule
Professional traders rarely risk more than 2% of their account on any single trade. Here's why this rule is so powerful:
- Even with 10 consecutive losses, you only lose 18% (with 2% risk)
- Preserves mental capital by avoiding emotional decision-making after big losses
- Allows compounding to work in your favor over time
- Gives you enough trades to let your edge play out
Beginners: Start with 0.5% Risk
When you're learning, risk even less. You're still developing your edge and emotional control. Once you have 50+ trades with consistent profitability over 3+ months, increase to 1%.
Common Mistakes to Avoid
Over-Leveraging on 'Sure Things'
Even 90% win rate setups lose. And when they lose, the stop hunt is often brutal because everyone saw the same 'sure thing'.
Ignoring Volatility Differences
A penny stock and a blue chip have different volatility profiles. Using the same stop percentage for both is incorrect.
Sizing Based on Dollar Amount
Asking 'how much should I invest?' is backward. Ask 'how much am I willing to LOSE?' then calculate position size from there.
Not Adjusting for Partial Exits
If you plan to scale out of positions, your initial position size needs to account for this from the start.
Frequently Asked Questions
How much should I risk per trade as a beginner?
Start with 0.5-1% risk per trade. This gives you room to make mistakes while learning. Professional traders typically risk 1-2% per trade after they've developed their edge. Once you have 50+ trades with consistent profitability over 3+ months, you can consider increasing risk.
What's the difference between position sizing and lot sizing?
Position sizing determines HOW MANY shares or contracts to buy based on your risk tolerance. Lot sizing is a forex-specific term referring to standard lots (100k units), mini lots (10k), or micro lots (1k). For stock swing traders, focus on position sizing based on dollar risk.
Can I use this calculator for options trading?
Yes, but you'll need to calculate risk per contract differently. Instead of (Entry - Stop), use the maximum you're willing to lose per contract (often the premium paid for long options). For advanced options strategies, you may need more specialized tools.
How do I calculate position size for multiple exit targets?
Calculate position size based on your FULL intended position, then scale out as planned. For example, if your full position is 200 shares, you might sell 100 at target 1 (50%), 60 at target 2 (30%), and 40 at target 3 (20%).
Should I adjust position size based on win rate?
No—keep risk consistent across all trades. Win rate should inform WHETHER you take a setup, not HOW MUCH you risk. If a setup type has less than 40% win rate, stop taking it. If it's above 50%, keep taking it with standard 1-2% risk.
What is position sizing in swing trading vs day trading?
The principles are identical, but swing traders often use slightly smaller position sizes because overnight risk is higher (gap risk). Day traders can use 2% risk more comfortably since there are no overnight gaps. Swing traders often use 1-1.5% to account for gap risk and longer holding periods.
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