Position Size Calculator
Enter account size, a risk amount or risk percentage, entry price, and stop price to calculate risk per unit, raw quantity, whole-unit quantity, notional position value, and whole-unit risk. This is country-neutral arithmetic and does not recommend how much risk you should take.
Use the position size calculator to translate a risk limit and a planned stop distance into a quantity. Enter account size, choose whether your risk input is a percentage of the account or a fixed amount, then enter the planned entry and stop prices. The calculator shows the monetary risk, risk per unit, theoretical quantity, whole-unit quantity, notional position value, and the risk represented by the rounded-down whole-unit quantity. It is useful for checking the arithmetic behind a trade plan, but it does not tell you what risk percentage, stop, or trade is appropriate.
How to use the position size calculator
- Enter the account size using the same currency as your prices and risk amount.
- Choose Risk percentage or Risk amount, then enter the risk limit you have already decided to use.
- Enter the planned entry price and stop price. The stop may be above or below entry; the calculator uses the absolute price distance.
- Review the theoretical quantity and whole-unit quantity together with the risk amount, per-unit risk, notional value, and whole-unit risk.
How position size is calculated
Risk per unit equals the absolute difference between entry price and stop price. For example, an entry at 100 and a stop at 95 creates 5 of risk per unit.
If risk percentage is selected, the calculator first converts it into money by multiplying account size by the entered percentage. A 10,000 account with a user-entered 1% risk value produces a 100 risk amount. This example explains the math only; it is not a recommended risk level.
Theoretical quantity equals risk amount divided by risk per unit. With 100 of risk and 5 of risk per unit, the theoretical quantity is 20 units. Whole-unit quantity is rounded down so it does not exceed the theoretical quantity when only integer units can be traded.
Notional position value equals theoretical quantity × entry price. Notional value can be larger than account size in leveraged or derivative markets, so it must not be interpreted as an approval of leverage or available margin.
The calculation does not include commissions, bid-ask spread, slippage, price gaps, contract multipliers, tick values, leverage, margin requirements, liquidation rules, taxes, currency conversion, or a stop filling at a different price. Those factors can make actual loss larger or smaller than the displayed amount.
Privacy, limitations, and investment notice
All inputs are processed locally in your browser. This calculator performs arithmetic only and does not recommend a risk percentage, position size, stop-loss level, security, or trade. The whole-unit result assumes one unit has the same price risk as the difference between the entered entry and stop. Futures, options, CFDs, leveraged products, and other contracts may require a multiplier, tick value, lot size, or other instrument-specific calculation that this tool does not apply. Market gaps and slippage can also cause losses beyond the planned stop distance. Verify contract specifications, broker rules, costs, and your own risk constraints before placing a trade.
Position size calculator FAQ
What does a position size calculator do?
It converts a user-entered risk amount and the price distance between entry and stop into a theoretical quantity.
Does this calculator recommend how much of my account to risk?
No. You choose the risk percentage or amount yourself. The tool does not provide a recommended value.
Why is the stop allowed above or below entry?
The calculator uses the absolute distance between entry and stop, so it can represent long or short price plans.
Why is there a whole-unit quantity?
Some instruments trade only in whole units. Rounding down avoids exceeding the theoretical quantity in that simple case.
Can I use fractional shares?
Yes. The theoretical quantity can contain decimals. Whether fractional trading is available depends on the broker and instrument.
Does it include commissions and slippage?
No. Those can change the real loss and should be considered separately.
Can I use it for futures, options, CFDs, or forex?
Only if one entered unit truly corresponds to the price difference used by the formula. Many such products use contract multipliers, tick values, lot sizes, leverage, or margin rules that this calculator does not model.
What if the stop gaps past my entered price?
Actual loss can exceed the planned amount because stops do not guarantee an exact fill price.
Is notional position value the amount I should invest?
No. It is simply theoretical quantity multiplied by entry price. It is not a recommendation or margin approval.
Are my account values uploaded?
No. The calculation remains in your browser.