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Trading Calculators

Position Size Calculator

How many shares or units to buy so a stop-loss hit risks only a set percentage of your account.

Also known as position sizing, risk per trade, lot size calculator.

Enter values

Results update as you type.

Result

Position size

100 shares

Amount at risk
$250.00
Position value
$5,000.00
Share of account
20%

About the Position Size Calculator

How many shares or units to buy so a stop-loss hit risks only a set percentage of your account.

Also known as: position sizing, risk per trade, lot size calculator, stock position size, position-risk.

How to use this calculator

  1. Enter account size, risk per trade, entry price, stop-loss price.
  2. The result updates instantly as you type — press Calculate (or Enter) at any time.
  3. Review the breakdown shown under the main result.
  4. Use Copy result or Share to save the answer or send a link with your inputs.

Position Size formula

Units = (account × risk %) ÷ |entry − stop|

Worked example

Using the values pre-filled in the calculator above:

  • Account size = 25,000
  • Risk per trade = 1 %
  • Entry price = 50
  • Stop-loss price = 47.5

the calculator returns:

  • Position size: 100 shares
  • Amount at risk: 250
  • Position value: 5,000
  • Share of account: 20%