Share | Cash Margin Calculator Use the Cash Margin calculator to compute the cash margin for any stock listed at Yahoo! Finance. Cash margin = (Total cash flow from operating activities - Capital expenditures) / Total revenue Cash margin represents the ratio of free cash to sales. For example, a company with a cash margin of 20% generates 20 cents of free cash for each dollar of sales. The financial data used in the calculator are annual values from Yahoo! Finance. Cash Margin Calculator Quote Symbol: NOTE: Indices starting with ^ not supported.