Risk and position sizing
Free Position Size Calculator
Enter your account size, the percent you accept to lose, your entry and your stop: the calculator returns how many shares to buy so that a stopped-out trade costs exactly that much.
Position size calculator
- Shares to buy
- 100 long
- Risk in dollars
- $100.00
- Position value
- $5,000.00
A stop below the entry is a long trade; a stop above it is a short. Shares are rounded down.
The calculator runs in your browser. Nothing you type is saved or sent anywhere.
Educational tool, not financial advice. The results only reflect the numbers you enter and say nothing about future returns. Trading involves a substantial risk of loss.
How to use the position size calculator
- Type your account size in dollars and the share of it you accept to lose on this trade, usually between 0.5% and 2%.
- Enter the price where you plan to buy and the price of your stop loss. A stop below the entry is a long trade; a stop above it is a short.
- Add a target if you have one, to see the reward-to-risk ratio.
- Read the shares to buy, the dollars at risk and the position value. The share count is already rounded down.
- Check that the position value fits your buying power. If it does not, buy fewer shares: the risk will be smaller than planned, never larger.
The position size formula in plain words
Your risk in dollars is the account times the risk percent. Your risk per share is the distance between the entry and the stop. Divide the first by the second and round down: that is the number of shares that loses your chosen amount if the stop is hit.
The stop sets the size, not the other way round: a wider stop means fewer shares for the same dollar risk. Gaps and slippage can make the real loss larger than planned, so treat the result as a ceiling.
Risk in dollars = account × risk %
Risk per share = |entry − stop|
Shares = risk in dollars ÷ risk per share, rounded down
Reward : risk = |target − entry| ÷ |entry − stop|
Worked example
A $10,000 account risks 1% on a long trade: entry $50.00, stop $48.50, target $54.50.
- Risk in dollars: $10,000 × 1% = $100.
- Risk per share: $50.00 − $48.50 = $1.50.
- Shares: $100 ÷ $1.50 = 66.7, rounded down to 66 shares.
- Position value: 66 × $50.00 = $3,300, about a third of the account.
- If the stop is hit: 66 × $1.50 = $99 lost. Reward to risk: ($54.50 − $50.00) ÷ $1.50 = 3.00R.
Commissions and slippage are not included.
Questions
How much should I risk per trade?
Many traders risk between 0.5% and 2% of the account per trade. At 1%, ten losses in a row cost about 10% of the account; at 5% they cost about 40%. Pick a level you could live with through a long losing streak, then let the calculator turn it into shares. More in risk management.
Does it work for short trades?
Yes. Put the stop above the entry and the calculator treats the trade as a short sale; the share count follows the same formula. Short selling has its own costs and risks, covered in short selling.
Why is the position value so much bigger than my risk?
Because you only lose the distance to the stop, not the whole position. Risking $100 with a $1.50 stop means holding $3,300 of stock. If that is more than your buying power, buy fewer shares and accept a smaller risk.
How do I choose the risk percent?
Start from your edge and your tolerance for losing streaks. The Kelly criterion calculator shows the most the numbers could justify, and the risk of ruin calculator shows how deep a bad run could go at each level.
UpTickFlow is our product. These guides are education, not financial advice. Trading involves a substantial risk of loss.