Position Size Risk Calculator

How it is calculated

You choose how much of the account you accept to lose if the stop is hit. The tool computes risk amount = account × risk% / 100 and risk per unit = |entry − stop|, then units = risk amount / risk per unit. The position value is units × entry. Because the absolute difference is used, a stop above the entry is treated as a short trade and gives the same sizing logic. The unit count is shown with two decimals and is not rounded down to whole shares, so round down yourself where fractions are not allowed. Risk must be above 0 and at most 100 %, all prices above zero, and a stop equal to the entry returns no result. Slippage, gaps and fees are not included.

Common mistakes

• Entering the risk as 0.01 to mean 1 %: the field is in percent, so 0.01 means a hundredth of a percent.
• Confusing the stop price with the stop distance: the field takes the price level, not the number of points.
• Rounding the share count up, which lets a stop-out cost slightly more than the chosen risk.
• Assuming the stop is guaranteed: gaps and slippage can fill it worse, so the real loss can exceed the risk amount.
• Ignoring the position value: a tight stop gives a large position that can exceed your buying power or available margin.