Position Size Calculator
Calculate a risk-based trading position size from account balance, risk percentage, entry price, stop-loss price and per-unit costs.
Calculator workspace
Enter your values, calculate, then review the assumptions shown with the result.
How this calculator helps
Calculate a risk-based trading position size from account balance, risk percentage, entry price, stop-loss price and per-unit costs. The calculator keeps the main answer with supporting values and the formula or method so the result is easier to check, compare and save.
Risk-based position sizing
A position size calculator starts with the amount of account equity you are willing to lose if the price reaches the stop-loss. The risk amount is account balance multiplied by the selected risk percentage. That amount is divided by the price distance between entry and stop, plus any per-unit trading cost you choose to include.
For example, a $10,000 account at 1% risk gives a $100 risk budget. If the entry is $100 and stop is $95, the price risk is $5 per unit. Ignoring fees, the theoretical position size is 20 units.
Why fees and slippage matter
Real trades can fill at a different price from the stop and can incur commission, spread or other costs. The optional per-unit cost field lets you reduce the position size to reflect an estimated extra amount, but it cannot guarantee the actual loss.
Notional value versus risk amount
Position notional is position size multiplied by entry price. It can be much larger than the risk amount because the stop-loss limits the planned price movement used in the calculation. Leverage, gaps and market liquidity can still make actual losses larger.
Use as arithmetic, not a recommendation
The calculator does not choose a security, recommend a risk percentage or tell you whether a trade is suitable. It only performs the position-sizing arithmetic from assumptions you enter.
How to use it well
- Use values from the source that actually applies to your situation.
- Check units, dates, rates and percentages before calculating.
- Review the formula/method and supporting figures rather than relying only on the headline number.
- For changing rates, regulations or policies, verify the current official source before an important decision.
- Use Copy Result or Save Result Image to keep the assumptions with the answer.
Frequently Asked Questions
What is risk per trade?
It is the percentage of the account balance used to define the planned maximum loss for the sizing calculation.
Does the result include leverage?
No. It shows units and notional value from entry price. Margin/leverage rules are broker- and product-specific.
Can actual loss exceed the calculated risk?
Yes. Gaps, slippage, fees, liquidity and execution can cause a different loss than the planned stop-distance model.