Position Size & Risk Calculator - Size Bots From Risk, Not Gut Feeling
Risk-first sizing: how many units, at what margin, and what win rate this trade needs - before the position exists, not after.
waiting for values…
How to read it
Risk-first sizing flips the usual question: instead of "how big a position do I want", it asks "how much can I lose if the bot is wrong". The calculator derives position size from your account and risk budget, then shows the leverage and margin needed, the net risk-reward after fees, and the win rate required just to break even. A single trade carrying half the account is a bet, not a position - most systematic traders risk 0.5-2% per trade.
Model and assumptions
Long-position model with the stop below entry. Fees are charged on entry and exit notional at your per-side rate; slippage and funding are not included, so treat the net reward-reward as slightly optimistic. The break-even win rate is 1 / (1 + R) computed on net (fee-adjusted) win and loss amounts - full edge math here.