How it works
The calculator uses fixed-fractional position sizing. Amount at risk = account size × risk per trade ÷ 100. Distance to stop = |entry price − stop-loss price|. Position size = amount at risk ÷ distance to stop, and position value = position size × entry price.
Worked example with the default values: 1% of 10,000 is 100. With an entry at 100 and a stop at 98 the distance is 2, so the position size is 50 units, worth 5,000, which ties up 50% of the account. If the stop-loss is above the entry, the result is read as a short position. If the position value is above 100% of the account, the trade only works with leverage or margin.
Limits: the result assumes the stop fills exactly at your price. Gaps, slippage, fees, financing costs and currency conversion can make the real loss larger. Contract multipliers (futures, options, CFDs) and lot sizes are not included, so convert the result into your instrument’s units and round down rather than up to stay within your limit. To check the setup itself, see the risk-reward calculator; for the theory behind how much to risk per trade, see the Kelly criterion calculator.