Price Formulas/Calculations: To calculate the selling price or revenue R based on the cost C and the desired gross margin G, where G is in decimal form: R = C / ( 1 - G) The gross margin is the Profit divided by the selling price or revenue R G = P / R So, the gross profit P is the selling price or revenue R times the gross margin G, where G is in decimal form : P = R * G The mark up percentage M, in decimal form, is gross profit P divided by cost C. M = P/ C M * 100 will change the decimal to a percentage.