FCF margin is the purest profitability measure: what percentage of revenue becomes free cash flow (operating cash flow − capex) available for dividends, buybacks, debt paydown, or M&A? A 15% FCF margin means $15 of every $100 in sales is distributable cash. FCF vs. EBITDA margin: FCF margin is always lower because it subtracts capex. A company with 25% EBITDA margin and 10% capex intensity has 15% FCF margin. Asset-light businesses (software, services) have FCF margins close to EBITDA margins. Capital-intensive businesses (telecom, utilities) have much lower FCF margins. Sector benchmarks: Software 20-35%, consumer goods 10-15%, industrials 5-10%.