Position Size Calculator
Calculate the exact number of shares, lots, or units to trade based on your account size, risk tolerance, and stop loss distance.
Track This Automatically with Disciplined
Disciplined tracks your position sizing discipline across every trade. See if you're consistently sizing correctly or taking too much risk.
- Real-time metric tracking
- Unlimited trade logging
- Professional analytics dashboard
- Free up to 50 trades
Understanding Position Sizing
The Foundation of Risk Management
Position sizing is arguably the most important decision you make on every trade. It determines how much you stand to lose if you're wrong — and it's the primary tool for controlling your risk of ruin.
The correct position size ensures that no single trade can do significant damage to your account, while still allowing you to capture meaningful gains when you're right.
The Fixed Fractional Method
The most widely used position sizing method is fixed fractional — risking a fixed percentage of your account on every trade. The formula is:
Position Size = (Account × Risk %) / |Entry − Stop Loss|
Why Most Traders Size Incorrectly
The most common position sizing mistakes:
- Using a fixed number of shares — this ignores the distance to your stop loss, creating inconsistent risk
- Sizing based on "feel" — emotional sizing leads to larger positions on worse trades (overconfidence) and smaller positions on good trades (fear)
- Not adjusting for stop distance — a tight stop should mean a larger position; a wide stop should mean a smaller one. The dollar risk stays constant.
- Ignoring account changes — as your account grows or shrinks, your position sizes should scale proportionally
A trading journal that tracks your actual risk per trade reveals whether you're following your sizing rules consistently — a key factor in long-term profitability.
Frequently Asked Questions
How do I calculate position size?▾
Position Size = (Account Size × Risk %) / Stop Loss Distance. For example, with a $25,000 account, 2% risk, and a $5 stop distance: ($25,000 × 0.02) / $5 = 100 shares. This ensures you never lose more than your predefined risk amount on any single trade.
What percentage should I risk per trade?▾
Most professional traders risk between 0.5% and 2% of their account per trade. Conservative traders and those with smaller accounts often stick to 1%. The key principle: your risk percentage should be small enough to survive a losing streak without significant drawdown.
Does position sizing work for crypto and futures?▾
Yes. The same formula applies to any asset class. For crypto, use the entry price and stop loss in dollar terms. For futures, convert the stop distance to dollar terms using the contract multiplier (e.g., ES futures = $50 per point).
Should I adjust position size based on volatility?▾
Yes. Many professional traders use ATR (Average True Range) to set stops, which naturally adjusts position size for volatility. In volatile conditions, your stop is wider so you trade fewer units. In calm conditions, tighter stops allow larger positions — the dollar risk stays constant.