Position Size Calculator: Risk per Trade, Stop Loss, and Shares
Position sizing translates a chosen account-risk budget, an entry price, and a stop price into a maximum number of shares. This calculator also accounts for estimated entry and exit slippage, round-trip fees, a maximum position-value cap, available capital, and a user-defined whole- or fractional-share increment. It supports structurally valid long and short setups, but it does not guarantee that a stop order will execute at the entered stop price. Quick answer A risk-based position size starts with the maximum dollars the trader is willing to lose if the planned exit occurs. Divide that risk budget, after fixed round-trip fees, by the estimated loss per share. Then apply any separate capital or concentration limit and round down to a share increment the broker actually supports. Risk budget = account balance x risk percentage Adjusted risk/share = |entry price - stop price| + entry slippage + exit slippage Risk-sized shares = (risk budget - round-trip fees) / adjusted risk/...