Position sizing is the process of determining exactly how much capital to allocate to a specific trade based on your account size, risk tolerance, and the trade’s specific setup. It is arguably the single most important skill in trading — even a strategy with a 40% win rate can be highly profitable with correct position sizing, while a 70% win rate strategy can lead to ruin with poor sizing.
The most widely used position sizing method is the fixed percentage risk model: risk a fixed percentage (typically 1–2%) of your total account per trade. The formula: Position Size = (Account Size × Risk %) ÷ (Entry Price − Stop Loss Price). This ensures that no single losing trade causes disproportionate damage to your account, and allows you to survive long losing streaks without significant capital erosion.
Other methods include the Kelly Criterion (mathematically optimal sizing based on win rate and risk/reward), fixed dollar risk (risk exactly $X per trade regardless of account size), and volatility-adjusted sizing (using ATR to size positions so that each trade risks the same dollar amount regardless of asset volatility).
Example: Account = $20,000. Risk per trade = 1% = $200. Trade: Buy BTC at $62,000, stop at $60,000 ($2,000 risk per BTC). Position size = $200 ÷ $2,000 = 0.1 BTC ($6,200 position). If stopped out: lose exactly $200 (1% of account). If target hit at $67,000: gain $500 (2.5% of account).
Learn more: Investopedia — Position Sizing Explained
