Free Cash Flow vs Net Income: Why Profits and Cash Aren't the Same

A company can report millions in profit while going broke, and that's not a hypothetical—it happens all the time.

Let me tell you about a retail company I watched implode in 2018. Beautiful income statement. Revenue growing at twelve percent annually. Net income margins expanding. The stock traded at eighteen times earnings, which seemed reasonable. Six months later, they filed for bankruptcy protection. What happened? They were profitable on paper but burning cash in reality. The accounting said one thing, the bank account said another, and the bank account always wins.

Net income is an accounting concept. Free cash flow is what actually happened to the money. Understanding this difference is not optional if you want to allocate capital intelligently. Most investors look at earnings per share, get excited about growth, and completely miss that the company might be incinerating cash to generate those earnings.

Start with net income. This is what's left after you subtract all expenses from revenue using accrual accounting. Accrual accounting means you record revenue when you earn it, not when you receive the cash, and you record expenses when you incur them, not when you pay them. This matching principle makes sense for understanding economic performance over time, but it creates a gap between reported profits and cash reality.

Here's a concrete example. You sell a million dollars of product in December on net-sixty terms. You record a million in revenue immediately. Your costs were six hundred thousand, so you book four hundred thousand in net income for December. Fantastic quarter. But you won't see that million in cash until February, and you already had to pay your suppliers, your employees, your rent. The profit is real in an accounting sense, but your checking account might be overdrawn. This is working capital timing, and it kills businesses.

Now let's build toward free cash flow. You start with net income, then you add back non-cash expenses. The big one is depreciation. If you bought a machine for a million dollars that'll last ten years, you don't expense a million immediately. You depreciate it at a hundred thousand per year. That hundred thousand reduces your net income, but you're not writing a check for it each year—you wrote the check when you bought the machine. So we add it back when calculating cash flow.

But here's where people get confused. They think depreciation is some accounting trick that makes cash flow look better than it really is. Wrong. Depreciation represents the fact that you already spent the cash in a prior period. Adding it back doesn't create cash—it just removes a non-cash charge from your starting point.

Then you adjust for changes in working capital. Working capital is current assets minus current liabilities. Think accounts receivable, inventory, and accounts payable. When receivables go up, that's revenue you recognized but haven't collected—it reduces cash flow. When inventory increases, you spent cash buying product you haven't sold yet—reduces cash flow. When payables increase, you're delaying payment to suppliers—that actually helps cash flow.

This is where high-growth companies often get destroyed. Revenue grows thirty percent, everyone celebrates, but receivables grow forty percent because you're extending generous payment terms to win customers. Inventory doubles because you're stocking up for anticipated demand. You're reporting profits, but you're funding growth with cash out the door. I've seen software companies with ninety percent gross margins run out of money because they booked revenue annually but paid customer acquisition costs upfront. The timing mismatch drains the treasury.

After working capital adjustments, you get to operating cash flow. This is cash the business generated from its operations. But you're not done, because you still have to maintain and grow the business. That's capital expenditures—the cash spent on property, plant, equipment, software development that gets capitalized. You subtract capex from operating cash flow, and now you have free cash flow. This is discretionary cash that could be returned to shareholders or used for acquisitions or paying down debt.

Free cash flow is what matters for valuation because this is the cash available to owners. Warren Buffett calls it owner earnings. A business is worth the present value of all future free cash flows. Not earnings. Cash flows. You can't pay a dividend with net income. You can't buy back stock with EBITDA. You need actual cash.

Let me give you a framework for when this difference becomes critical. Capital-light businesses—software, asset managers, consulting firms—usually have free cash flow close to net income. Low capex, minimal working capital, high conversion. These are beautiful business models. You can trust the earnings because they translate to cash.

Capital-intensive businesses—airlines, utilities, manufacturers, telecom—have persistent heavy capex requirements. They might report solid net income, but after you subtract maintenance capex just to stand still, free cash flow is a fraction of earnings. An airline might earn two billion but need one-point-eight billion in capex to replace aging planes and maintain operations. The real economic profit is two hundred million, not two billion.

Then you have growth businesses consuming cash to fund expansion. Amazon did this for years. Profitable on GAAP accounting but free cash flow negative because every dollar was reinvested in fulfillment centers, technology, inventory. This is fine if the investments generate returns, but you have to evaluate whether the capex is maintenance or growth, and whether growth capex is earning an adequate return on invested capital.

Here's what I look for when evaluating cash generation quality. First, free cash flow conversion rate—free cash flow divided by net income. Above eighty percent is strong for most businesses. Below fifty percent needs explanation. Second, I look at the trend over three to five years. Consistent conversion means predictable cash generation. Volatile conversion suggests working capital swings or irregular capex, which makes valuation harder.

Third, I adjust for one-time items. A company might generate huge free cash flow one year because they cut inventory or stretched payables. That's borrowing from future quarters. Unsustainable. I normalize for these timing effects to understand the true run rate. Fourth, I separate maintenance capex from growth capex. The company won't tell you this cleanly, so I look at capex as a percentage of revenue over time and compare to industry peers. If capex is consistently four percent of revenue and suddenly jumps to seven percent, that's probably growth investment.

The valuation implications are direct. If you're paying twenty times earnings for a company that converts sixty percent of earnings to free cash flow, you're really paying thirty-three times free cash flow. That multiple might be too expensive. Conversely, a company trading at fifteen times earnings with one hundred ten percent free cash flow conversion is really at thirteen-point-six times cash flow. Much more attractive.

One more pattern worth knowing. Watch for companies that consistently report earnings growth but flat or declining free cash flow. This is a red flag. They're likely growing through accounting choices—recognizing revenue aggressively, capitalizing expenses that should be expensed, building inventory and receivables. The income statement looks great, the cash flow statement reveals the truth. Enron, Valeant, Luckin Coffee—this pattern showed up in all of them before the collapse.

The inverse also happens. Businesses with lumpy capex cycles might show depressed free cash flow in heavy investment years, then massive cash generation in subsequent years. Misunderstanding this cycle causes mispricing. If you buy during the investment year when free cash flow is temporarily depressed, you can get a good business at a discount.

Cash is reality. Earnings are opinion. Accounting rules allow discretion, judgment, estimates. Cash is what showed up in the bank account. When the two diverge persistently, trust cash flow. It'll tell you what's really happening in the business while the income statement tells you a story.

See you Friday. The income statement tells you how much you might make; the cash flow statement tells you how much you actually made.