Position size calculator
Risk a fixed, small slice of your account on every trade. Enter your numbers and get the exact share size and the cash you're putting at risk if the stop is hit.
How position size is calculated
Shares = (Account × Risk%) ÷ |Entry − Stop|
The idea is simple: decide the most you're willing to lose on a trade (a small % of your account), then size the position so that hitting your stop costs exactly that — no more. It keeps any single trade from doing real damage, which is what lets a strategy's edge play out over many trades.
How much should you risk per trade?
- 0.5%–1% — conservative; survives long losing streaks comfortably.
- 1%–2% — common; a balance of growth and safety.
- > 2% — aggressive; a handful of losses can carve a deep hole. See what drawdown that implies.
Position sizing is part of the strategy
The same rules with different sizing produce completely different drawdowns and Sharpe ratios. QUANTHEON Lab models position sizing bar by bar inside the backtest, so the equity curve you see reflects how you'd actually size — not an idealised one-share simulation.
FAQ
How do you calculate position size?
Position size = (account size × risk per trade %) ÷ (entry − stop). The top is the cash you're willing to lose; the bottom is the loss per share if the stop hits.
How much should I risk per trade?
Commonly 0.5%–2% of equity, so a losing streak doesn't threaten the account. Lower risk means smaller drawdowns but slower growth.
What if my position is bigger than my account?
That means the trade needs leverage/margin to take the full size — tighten the stop or lower the risk % to bring it within your cash.
Related: Sharpe ratio calculator · Max drawdown calculator · How to backtest a strategy