Position Size Calculator
How many shares or units fit the share of your account you accept to lose if the stop price is hit, with the loss at the stop, the position value and the risk-reward ratio.
Result…
How it's calculated
Risk budget = account × risk % Risk per unit = |entry − stop| Units = risk budget ÷ risk per unit (rounded down to whole units) Loss at the stop = units × risk per unit Position value = units × entry Risk-reward ratio = |take-profit − entry| ÷ |entry − stop|
Position sizing fixes how much you could lose on a trade before you place it. Choose the share of your account you accept to lose, set the stop price where the trade is wrong, and the number of units follows: the money you are willing to lose divided by the loss on each unit between the entry and the stop. A closer stop allows more units for the same risk; a wider one fewer. With a take-profit price the page also gives the risk-reward ratio, the reward per unit divided by the risk per unit. It works for long trades (stop below the entry) and short trades (stop above). Whole units are rounded down so the loss stays inside the budget. The result is arithmetic on the numbers you enter, not a recommendation to trade.
Your numbers, step by step
About the Position Size calculator
This position size calculator works out how many shares or units fit the amount you accept to lose on one trade. Enter the size of your account, the share of it you are willing to risk, the entry price and the stop price, and it divides the money at risk by the loss on each unit between the entry and the stop. It works for long trades, with the stop below the entry, and short trades, with the stop above. Add a take-profit price and it also gives the risk-reward ratio and the profit if that price is reached. Whole units are rounded down so the loss stays inside your limit, and every step is shown with your numbers. It is a way to set the size of a trade before you place it; it does not say whether any trade is a good idea. For the return on a finished trade, use the ROI calculator.
How to use it
- Choose “Long (buy)” or “Short (sell)”.
- Enter the “Account size” and the “Risk per trade” as a percentage of it.
- Enter the “Entry price” and the “Stop price”, and optionally a “Take-profit price” for the risk-reward ratio.
- Pick “Whole units” or “Fractions allowed”, then read the position size, the loss at the stop and the position value.
Worked example
With an account of 20,000 and a risk of 1.5% per trade, the most you accept to lose is 300. Buying at 120 with a stop at 114 risks 6 per share, so 300 ÷ 6 = 50 shares. The position is worth 6,000, which is 30% of the account. With a take-profit price of 135 the reward is 15 per share, a risk-reward ratio of 2.5, and reaching it would make 750.
Updated
Questions people ask
How do I calculate position size from my stop loss?
Multiply your account by the percentage you accept to lose to get the risk budget, then divide it by the distance between the entry price and the stop price. The result is the number of shares or units.
What is the formula for the risk-reward ratio?
Divide the distance from the entry to the take-profit price by the distance from the entry to the stop price. A ratio of 2.5 means the possible gain is two and a half times the possible loss.
Why can the position be worth much more than the money I risk?
The risk is only the gap between the entry and the stop, not the whole price. A close stop allows many units, so the position value can be a large share of the account, or more than all of it, which needs margin.
Can I lose more than the loss at the stop?
Yes. A stop order is not guaranteed to fill at its price: prices can jump past it overnight or in fast markets, and fees, spreads and financing add to the cost. The figure here is the loss if the stop fills exactly.
What percentage of my account should I risk per trade?
There is no single right figure: it depends on your circumstances, the market and how much loss you can afford. This calculator is educational, not trading advice, so speak to a licensed financial professional before trading.