Position Size Calculator
Size a trade by risk, not by hunch.
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Position Size Calculator by TheCalcTools
How the Position Size Calculator works
Enter your account size, the percentage you are willing to lose and your planned entry and stop prices.
The risk per share is the gap between entry and stop.
Shares equal the money at risk divided by the risk per share, rounded down.
The formula
Worked example
Using the default values shown in the calculator:
| Account size | $10000 |
|---|---|
| Risk per trade (% of account) | 1 % |
| Entry price | $50 |
| Stop-loss price | $48 |
- Money at risk = 1% × $10,000 = $100.
- Risk per share = $50 − $48 = $2.
- Shares = $100 ÷ $2 = 50, a position of $2,500.00 (25.0% of the account).
Result:
| Shares to buy | 50 |
|---|---|
| Dollar risk | $100.00 |
| Position value | $2,500.00 |
| Position as % of account | 25.0% |
Frequently asked questions
Why size by risk?
It keeps any single loss to a planned fraction of your account, however volatile the stock is.
Is this financial advice?
No. Trading carries a risk of loss. Gaps and slippage can make real losses larger than planned.
Sources and further reading
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This calculator gives estimates for information only. It is not financial advice, and your lender's or provider's figures will govern. Rates, fees and rules vary. See our disclaimer.