Free cash flow: the number earnings can't fake
Why sophisticated investors read the cash flow statement first.
Net income is calculated according to accounting rules that involve estimates — of depreciation schedules, of future bad debts, of when revenue is truly "earned." Free cash flow asks a blunter question: how much actual cash did the business generate, minus what it had to reinvest to keep running? Cash received is not an estimate.
The definition
Free cash flow = cash from operations − capital expenditures. Cash from operations is real money collected from customers minus real money paid to suppliers and employees. Capital expenditures are the physical reinvestment — machines, buildings, servers — required to sustain and grow. What remains is the cash genuinely available to owners: for dividends, buybacks, debt paydown, or acquisitions. It is the number Warren Buffett calls "owner earnings," and it is the basis of essentially every serious valuation model.
When earnings and cash diverge
The gap between net income and free cash flow is where stories live. Earnings high, cash low: the company may be booking sales it has not collected (watch receivables swell), or stuffing inventory, or capitalizing costs to push expenses into the future. Sustained for years, that pattern precedes many accounting scandals — Enron reported profits to the end; the cash never matched. Earnings low, cash high: often a heavy depreciator whose assets outlast their accounting life, or a subscription business collecting cash upfront. These can be quiet bargains.
One honest complication
Capital spending mixes maintenance with expansion, and companies rarely separate the two. A railroad spending heavily to lay new track shows weak free cash flow while building future earning power. So read capex with context: is it sustaining the old business or buying a bigger one?
The habit that follows: whenever a profit number surprises you — good or bad — open the cash flow statement and check whether the cash agrees. Over one quarter, they often differ innocently. Over five years, a business is what its cash flow says it is.