Position Size Calculator
Calculate optimal trade position size.
Step-by-Step Solution
About Position Size Calculator
Calculate optimal trade position size. This calculator provides instant results with step-by-step explanations to help you understand the calculation process.
How to use this calculator
- Enter your account balance and the amount you want to risk on the trade.
- Enter your entry price and stop loss price.
- Calculate the price difference between entry and stop loss.
- Use the result to find the position size the trade should not exceed.
The formula explained
$$ \text{Position Size} = \frac{\text{Account Equity} \times \text{Risk per Trade}}{\text{Entry Price} - \text{Stop Loss Price}} $$
- \(\text{Position Size}\) = the number of units, shares, or contracts to trade
- \(\text{Account Equity}\) = your total account balance or trading capital
- \(\text{Risk per Trade}\) = the fraction or percentage of your account you are willing to lose on one trade
- \(\text{Entry Price}\) = the price at which you enter the trade
- \(\text{Stop Loss Price}\) = the price where the trade is closed to limit loss
Step by step method
- Start with the amount of money in your account and decide how much of it you can lose on this trade.
- Find the distance between your entry price and stop loss price.
- Divide the dollar risk by that price distance to get the position size.
- Check that the final size matches the instrument you are trading, such as shares or contracts.
Worked example
Suppose a trader has a $10,000 account and wants to risk 2 percent on a stock trade.
- Calculate the risk amount: \(10{,}000 \times 0.02 = 200\).
- Find the price distance between entry and stop loss: \(50 - 47 = 3\).
- Divide the risk amount by the distance: \(200 \div 3 = 66.666...\).
- Round to a practical trade size, such as 66 shares if whole shares are required.
Answer. 66 shares
Tips and common mistakes
- Always base risk on the stop loss distance, not on the full trade value.
- Make sure the entry and stop loss are in the same price units before calculating.
- If your broker or market requires whole units, round down to avoid exceeding your risk limit.
- Recalculate position size whenever your account balance or stop loss changes.
Frequently asked questions
What does a position size calculator do?+
It helps you determine how much of an asset you should buy or sell based on your account size and risk limit. The goal is to keep one trade from costing more than you planned. It is especially useful for managing risk consistently.
Do I need to enter a stop loss?+
Yes, in most cases the stop loss is essential because it defines how much you could lose per unit. Without it, the calculator cannot measure risk per trade accurately. The result is only meaningful when the exit point is clearly defined.
Can I use it for stocks, forex, or crypto?+
Yes, the same idea applies across many markets. You just need to use the correct price values and make sure the position size matches the asset type you trade. Some markets use lots or contracts instead of shares.
Why does the calculator tell me to round down?+
Rounding down helps keep your actual risk at or below your target. Rounding up can push the loss above what you planned if the trade reaches your stop loss. Conservative rounding is a common risk management habit.
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