Position Size Calculator
Work out how many shares to trade so a stop-loss costs you only the amount you're willing to risk
Trade Setup
Below entry to buy, above to short
Optional; 0 to skip
Caps the size; 100% means no leverage
Buy
100 shares
Risking $250.00 (1.00% of the account) if the stop is hit · position $5,000.00
Position value
$5,000.00
20.0% of your account
Risk per share
$2.50
entry to stop-loss
Reward-to-risk
2.40 : 1
$600.00 profit at the target
Break-even win rate
29.4%
share of trades you must win to break even
Profit or loss by exit price
100 shares bought at $50.00
Position Size at Different Risk Levels
| Risk per Trade | Shares | Position Value | Money at Risk |
|---|---|---|---|
| 0.25% | 25 | $1,250.00 | $62.50 |
| 0.5% | 50 | $2,500.00 | $125.00 |
| 1% | 100 | $5,000.00 | $250.00 |
| 1.5% | 150 | $7,500.00 | $375.00 |
| 2% | 200 | $10,000.00 | $500.00 |
| 3% | 300 | $15,000.00 | $750.00 |
| 5% | 500 | $25,000.00 | $1,250.00 |
Why Position Sizing Matters
Position sizing decides how much you lose when a trade goes wrong. Instead of buying a fixed number of shares, you choose the most you're willing to lose, often 1% to 2% of the account, and the distance to your stop-loss sets the share count. A run of losses then shrinks the account slowly instead of wiping it out.
The Formulas
Risk budget = account × risk %
Shares = risk budget ÷ |entry − stop|
Break-even win rate = 1 ÷ (1 + reward-to-risk)
Slippage and gaps can make a real loss bigger than planned.
Risk Management Tips
- •Many traders risk 1% to 2% of the account per trade
- •Set the stop where the trade idea is wrong, then size the position
- •Aim for trades with at least 2:1 reward-to-risk
- •A stop doesn't protect you from overnight gaps
- •Track your actual win rate and average reward-to-risk