Risk calculator
Position Size Calculator
Estimate whole-share position size for USD-priced stocks and ETFs from a USD risk budget and stop distance.
Educational use only. Not financial advice. Results are estimates. Trading involves risk. Read full disclaimer.
This calculator estimates whole USD-priced stock or ETF shares under your entered account, planned-risk, stop-price and fee assumptions. It does not support futures, forex, options or cryptocurrency. It does not check buying power or recommend a suitable position. Stop execution is not guaranteed: gaps, slippage, liquidity and costs can cause realized loss to exceed planned risk.
Position Size Calculator
Results
Planned Risk Budget
$100.00
Planned Risk Per Share
$5.00
Position Size
20 shares
Position Value
$2,000.00
USD-priced stock/ETF shares only; account and fees must be in USD. Whole-share estimate, not a buying-power check. Gaps, slippage, liquidity and fees can cause realized loss to exceed planned risk.
How to Use This Calculator
- Enter your account size: Your total trading capital or account balance.
- Set your risk per trade: The percentage of your account you're willing to risk (your chosen assumption).
- Enter your entry price: The price at which you plan to enter the trade.
- Enter your stop loss price: Your intended stop price; actual execution may differ.
- Optional: Add commissions/fees: Enter any trading fees or commissions for this trade.
- Review the results: The calculator shows your dollar risk, risk per unit, position size, and total position value.
Formula
Dollar Risk = Account Size × (Risk % ÷ 100)
Risk Per Unit = |Entry Price - Stop Loss Price|
Available Risk = Max(0, Dollar Risk - Estimated Commissions/Fees)
Position Size = Floor(Available Risk ÷ Risk Per Unit)
Common Mistakes to Avoid
- Using the formula for contracts or non-USD instruments.
- Treating modeled risk as a guaranteed maximum loss.
- Ignoring fees, liquidity or buying-power requirements.
Frequently Asked Questions
What instruments are supported?
Only whole shares of USD-priced stocks and ETFs, using a USD account risk budget and USD fees. Contract multipliers and currency conversion are not supported.
What risk percentage should I enter?
Enter your own planned-risk assumption. The calculator does not determine what risk is appropriate for your account or circumstances.
How are fees handled?
The entered total round-trip fee estimate is subtracted from the planned risk budget before dividing by stop distance. Actual fees and fills may differ.
How does stop distance affect size?
For the same risk budget, a tighter stop means less planned loss per share and a larger calculated position; a wider stop means a smaller position. Neither guarantees execution or makes the trade suitable.
Can losses exceed the entered risk?
Yes. Gaps, slippage, liquidity, order execution and costs can produce a loss beyond the planned amount.
Why reject equal entry and stop prices?
Zero stop distance cannot support this sizing formula.
Why round down?
The estimate rounds down to whole shares so modeled stop-distance loss fits within the remaining budget. This is not a cap on realized loss.
Does position value mean I can afford the trade?
No. Position value is shares multiplied by entry price. Buying power, short-sale availability and broker restrictions must be checked separately.