Position sizing is the part of trading that decides whether a losing streak is a setback or the end of the account. This calculator sizes a trade so that if price hits your stop-loss, you lose exactly the percentage of your account you decided to risk — no more.

It updates as you type and runs entirely in your browser. Nothing is stored.

Risk amount—
Position size—
Position value—
% of account—
Position vs. account

Risk-based position sizing: the calculator sizes the trade so that hitting your stop-loss loses exactly your chosen risk percentage of the account. A position value above 100% of your account requires leverage. This is an educational tool, not financial advice.

How the math works

The logic is deliberately simple, because position sizing should be:

  1. Risk amount = account size × risk per trade. Risk 1% of a $25,000 account and you’re putting $250 on the line per trade.
  2. Risk per unit = the distance between your entry and your stop-loss. A $100 entry with a $92 stop risks $8 per unit.
  3. Position size = risk amount ÷ risk per unit. $250 ÷ $8 = about 31 units.
  4. Position value = position size × entry price — the capital the position actually controls. If that exceeds your account, you’d need leverage.

Why fixed-fractional risk matters

The point of sizing every trade to the same small percentage is survivability. A trader who risks 1% per trade can be wrong ten times in a row and still have roughly 90% of their account. A trader who bets big to “make it back” can be wiped out by a single bad run. Signals decide direction, but size decides whether you’re still around to trade next month — the same reasoning behind reaching your first $10k without blowing up.

This tool is for education and is not financial advice. Leverage amplifies losses as well as gains.